The right carburetor for my mild built 350 small block chevy?

A 750 Holly Double Pumper might be a little too much carb for this engine. You can use it but you might want to decrease the jet size a couple sizes. Holly makes a street eliminator series carb that should work great for your engine. They look allot like a double pumper but thy have vacuum secondaries. I use one on my street driven 383 and it flows plenty of fuel/air. A true double pumper is really only good on high RPM race apps.