Your car must be an early 65 where the timing cover is the rear plate of the pump.  You must use the correct pump.  Early 65 aluminum.  They are available.
The 66 and later pumps had their own backing plate and sealed alot better.  Be sure to use sealer on all threads.  I once tinned some washers with lead solder to keep the adjusting bolt for the alternator from seeping water.

If Im doing a 5.0 swap, and using V belts, can I use the early 65 waterpump?  I want to use an alumn pump instead of cast iron.  I bought a new timng cover w/ dipstick infront, but not sure how to tell if i can use early 65 alum. Pump.

Thanks Steve.
so does it matter if it is 66-69 OR 70-79?  I know the lower outlet matters, but 66 is opposite of 69 (I think) so what other difference is there for say, mid 70's?

The 67 coupe I own has a 69 302 in it. I'm building a 347 stroker from a 71 block that I got for a little of nothing. Does that mean I have to change radiators if I install the 71 with the inlet of the water pump on the other side?

kdgt500 wrote:

The 67 coupe I own has a 69 302 in it. I'm building a 347 stroker from a 71 block that I got for a little of nothing. Does that mean I have to change radiators if I install the 71 with the inlet of the water pump on the other side?

Use the 69 302's timing cover, pointer, balancer and pulleys and you can use the 69 water pump with the inlet on the driver side.

The engine block does not care what timing cover goes on it, but the balancer must match the crankshaft balance.  If your 347 uses a 28 ounce balancer, your 69 302 stuff will work fine.  Note timing pointers are on opposite sides between 69 and 70, so balancers are marked differently.