Hi, welcome to the best Mustang forum ever. Got more info on what kind of use you will be subjecting the vehicle to.
As for carbs I do like Holley but not mechanical secondaries. For general use vacuum seco’s seem to work better.
You can’t get much better than Ford “Duraspark” distributors, replacement parts available just about anywhere.
Lots of guys here will chime in with other trustworthy suggestions I am sure

I'm not a huge fan of Holleys.  They are harder to tune and don't seem t hold the tune as long or as well as an Edelbrock. 

My 289 (.030 over) had the Edelbrock Performer intake, cam, and 1406 carb (600 cfm).
Very peppy and fun even with c4/2.80 gears and more fun with c4/3.25 Currie traction lock.
I had 69 351w heads for both combos as well with Edelbrock springs for 351w.
Nothing fancy, still fun.  My primary driving was city/highway driving, no track.

My wife’s truck has a straight 6, 300 cid with a Holley Truck Avenger carb (470 cfm) came with truck.
Played with it recently...by necessity...but was actually surprised how easy it was to work on.
Runs well.

Last time I had a Holley on a car was over 25 years ago.
Guess I learned a bit from these guys here.

Last edited by Nos681 (9/29/2020 10:30 PM)

Worth mentioning. 

Quick Flow carbs are identical to Holley, with some improvements.  One is adjustable vacuum secondaries.  I have been running one on my car for a few yesrs now.

I disagree the Holleys “lose tune”.  What is to lose?   I agree they are more challenging to “find the tune”, but once dialed in, nothing ever changes.  I agree smaller is better. Clevelands inherently suffer from slower fuel mix and flow due to the huge ports and runners.  Don’t make it worse by putting too large a carb on it.  650 is just about right but a 600 will have better throttle response.

Let me clarify about losing tune: the Holleys sold today are a bit different than the ones from years ago, which were decades old at the time I was tuning them.  I could get the tune right, but over time, especially on things that sat, the tune would go off and require me to mess with it again.  Possibly my experience with them was more of an issue caused by age and wear than the inherent design of the Holley. 

That said, the issue of getting the whole fuel curve right on a Holley is 100% real.  Most other carbs I've tuned over the years were easier to get dialed in so that the entire curve was optimal, not just idle and WOT. 

In the end, people gravitate to what they are comfortable tuning.  Years ago I became quite familiar and comfortable tuning Q-Jets and Carters, so the Edelbrock carbs I prefer now were a simple transition.  I did a lot of off roading at one point and Holleys are utter garbage for that due to the end mounted float bowls.

Absolutely go with the smaller carb.  We get people on here all the time trying to tune a 650 on a mostly stock 289 or 302 and they just don't want to hear that they would be much better off with a 500cfm carb, because its a better match for the engine.  Peak flow is only really important if you race the car.  For street driving you will be much happier with a smaller carb that responds on the low end. 

Stevo wrote:

TKOPerformance wrote:

For street driving you will be much happier with a smaller carb that responds on the low end. 

Giddy up to that... Jon Earnhardt set me straight on this in 2002. Hence why I still have the Autolite 4100 on my car. Perfectly matched for the 289...

"Soooooooooooooooooo....you're say'in a tunnel ram with twin 750's would NOT be a good choice for my stock 289?!  Bummer!
How bout I put a big-honk'in-snotty-roller cam in it? Would that help it?
What sort of gas mileage do you think I might be  able to get..........it's my daily driver!
My friend Bubba knows a guy who's cousin bought a FACTORY 454... 66 Mustang! He sez he gets 20-25 MPG and runs regular gas in it! Would mine get about that much?"