I have Carolina engines, 580ci, 1071 blowers set at around 730hp with 6lbs boost. I am happy with the engines, only time I broke them was due to BAD gasoline.
I think the way to go is with an EFI engine, I know Tomy at Chief has been working on those and is getting great results.
I personaly will go with a new Mercury 500 EFI Wipple Charged and the B-Max drive.
If you go with an engine builder I like Carolina, Chief, Eickert, Sterling and Zul. The reason I like them is because I know they will stand behind their engines and I base that on my personal experience ( Carolina) and the experence of my friends in the Poker run circuit and Racing circuit ( the other builders)