273 Carb Questions/recommendations

List what was don'e to the engine, the details and what the intended purpose of the build is. Also, if you please, the cars rear gear ratio and stall speed of the tranny.

A 500 would be good for stock to very mild build up parts.
A 600 would be better if the axle ratio was higher than normal and the engine was tweaked up a bit more than how one may think it may be.

I like the AFB carbs because they are very reliable and user freindly carbs that are forgiving. They stay where you set them and have little issue once set up.