Put a s/c on the big block. If it is a car you drive often I would say go with a supercharger. If you have an auto I would put a twinscrew on it. If you are going to go with a centifugal supercharger Vortech is the best when it comes to reliablity and service but they tend to make alittle less power. I have heard lots of bad things about Powerdyne's. If you put a big block in you are going to add weight in the front of the car making it handle a little worse and you are going to have less space to work with when you need to work under the hood.