What size carburetor should I be using LA 360 engine?

It might PERFORM better in a race with a 750, but it certainly should run like a champ with that 670 and perform well at idle, going down the road, and wide open throttle. Actually, it would run like a champ with a factory 360 2bbl. I have a 670 on my 5.9 magnum and on my 318 in my '80 Dodge truck. Both work great!!! I agree with RRR, learn to work on this older stuff.