Both high and low pressure switches cannot go in the same line, it frankly makes no sense.  The system has a high pressure side and a low pressure side.  High pressure gas comes out of the compressor, goes through the condenser where it condenses back into a liquid, which travels through the orifice tube into the evaporator where it becomes a low pressure gas routed through the filter/dryer, and back to the compressor to start the cycle over again.  The high pressure switch is typically in the line from the compressor to the condenser.  The low pressure switch wold be in the line from the evaporator to the compressor (after the filter/dryer). 

I need more info on your gauge readings.  What was the ambient temp when taking those readings?  Something is off, because at 220 on the high side the low side should be more like 50, at about 80 degrees ambient. 

Based on info I got off the internet it says the gages should read in the neighbor hood of  2 X OAT plus 50 and the LO should be around 30 to 40. The HI was right on the other day when I checked it from a cold start at idle and the LO was too. I went and drove around the big block and the compressor started to squeal so I came home. I tried to put the gages on while it was running and could not do so due to the high pressure. Shut it off and let it cool down for a little bit and then put the gages on and started it up. The high reading went above 500 psi. I haven't run it since. Again I read that if the compressor is putting out over 300 psi that it is considered OK. But the squeal concerns me. I thought I could open it up to look at it and rebuild but I can't find parts for it. Last year I took it to my mech and he flushed it and installed a new expansion valve, dryer, and evaporator temp switch. Till recently it's been OK but started running warmer and warmer. I called CCA to order Hi and LO switches. The only information I got was, after I clean it out and install the new compressor, dryer, and expansion valve was to put exactly 24 ozs. of R134a in the system. Curt then told me to order the switches on line out of the catalog. I don't see any for 1970 Fords. I saw the switches and that manifold thing in the Chevy catalog but I don't know anything about Chevy AC systems. I'm worn out working on the AC system and going through compressors. Granted it's probably all my own doing so when I   sabatoge myself I need to have some kind of system protection devices.

MS ---  It was vacuumed when I originally installed this current compressor. I did it for 2 hours. That was the only time it actually worked as it should have after converting it to R134a. Then I accidentally loosened the high pressure hose on the compressor. I didn't vacuum it cause it still had pressure in it but low so I recharged it. After awhile it started squealing. The system was then evacuated and flushed. The dryer, expansion valve, evaporator thermostats was replaced. It was vacuumed and recharged. It only cooled to 50º. We went on the bash and it was so-so and getting warmer and warmer to where it is today. 

Bolted --- This car never has had a switch on it. I think I need both the HI and LO switches so when pressureizes like it does now it will cut off and when it runs to low on freon it will cut off. I would like to add a WOT switch to it also so that it will cut off when I might need to pass MS. The compressor is supposed to be good for 6000 RPM. The engine is good for 5500 RPM. The math indicates that I Ok but I think a WOT switch would be good. I have gone through two Sanden type compressors before this real Sanden. I don't know enough experiance with R134a to know how it exactly works compared to what I used to know with R12. I will defiantly look into the Motorcraft compressor but I'll need to protect it from me.

I'm with Bolted on this, I think the system is plugged somewhere.  Situations like this I tend to suspect the orifice tube first, but a plugged or partially plugged evaporator is also a possibility.

Here's a link to the guidelines for R134a as far as system pressures vs. ambient temp:

https://rechargeac.com/how-to/ac-system-pressure-chart

I've been looking for parts and doing a little research on the compressor. The Motorcraft compressor intrigues me but I don't find any info on it or any specifications except that they are out there. I looked at Rockauto but just found part numbers. I did find that the condenser has to be replaced and a disc type filter needs to be installed for warranty purposes. I also found that the evaporator that I have and the 134a evaporator are way different.

R134a definitely needs more surface area than R12.  Its common to upgrade to a larger condenser when making the switch, and it would also make sense that in a properly designed system the evaporator would be different as well. 

In general I'm not a fan of reman compressors.  I've just had too many of them that lasted all of 1-2 years and failed again.  I would suggest looking at just rebuilding it yourself.  They aren't terribly complicated.  Rebuild parts are usually absurdly cheap (like $35 for everything).  You'll need to know the specific model, but these guys have rebuild parts:

https://www.shopcenturyautoair.com/store/c19/Sanden.html

If you're running R134a, make sure you use the right oil.  If the system had R12 in it at one point you need to make sure you either get all the old oil out, or use conversion oil.  Personally when changing a system over I will replace the condenser, lines, and at the very least thoroughly flush the evaporator.  Then when I rebuild the compressor I start with the right oil for lubrication of the seals, etc.  It should be PAG for R134a. 

You don't need to open the box the check the evaporator.  I've always done it by flushing the evap through the hoses coming through the firewall, then leak testing with vacuum.  If its the culprit its not completely plugged.  My guess would be it caught some "black death" from the previous compressor failure.  You should be able to flush it out.

Sorry it's Classic Auto Air the Original Air Group.   wwworiginalair.com     
I originally was told I didn't need an evaporator but that I did need a condenser for 134. So Installed a new one. Im told that I need a new expansion valve but I can't figure out how the expansion valve gets contaminated based on direction of flow. I'm thinking I could just replace the expansion valve, flush the entire system and recharge it then it would be Ok. I'm wondering where CAA gets their information on the amount of freon to use. It doesn't add up. However to get the gage numbers higher where I'm told they should be it would need close to 36 ozs. If I were to install the bigger evaporator how much freon should it take?

Rich, I learnt more bout A/C on that visit than I've ever known before.
Thanks.

Is there a modern day replacement for the black tar that wraps around the expansion valve? I've never liked that goo.