Holley or Edelbrock

We run a Thunder 800 AVS on a stock 74 26K original mile 440 (headers, orange box and 2.5 duals are only mods).

I only set it on the intake and adjusted the idle screws. That was 4 years ago. We put about 3K miles on it so far. It just runs perfectly.
I start the car once a week, warm it up good. And we drive it several times a year.

Ok, they make a 650 cfm AVS Thunder series. That is what I suggest for a low maintenance carb. On the other hand, my 74 360 came with a TQ, so I believe they are 800 cfm. If you were planning on running more power later I would just buy the 800 AVS and then you would only have to buy the carb once for your future power needs. Jet accordingly for the basic motor. Re-jet a little bigger for your next motor.
:)