318 simple bolt on setup for more horsepower

What would be a good 4 barrel carburetor for that setup
Depends what the rest of your build is going to be like. You could just get an eddy 1406 (since they are very simple to tune and get accustomed to) or a holley double pumper and really let that motor scream. The carb that goes on should be directed correlated to how aggressive the rest of the setup is going to be and how much fuel the engine will want. For something like this though, I would just suggest that 1406 due to that it is an easy carb to tune, is very versatile and in the future if you choose to replace it, easy to sell.