I know Best Machine has used the Indy 440-3x with adapters on B1 engines. I did an FBS single dominator manifold once. Its basically a B1 manifold with the flange end altered to fit FBS heads. Cut the floor out and raised it in the plenum area and reduced the runner taper a bit. Had 121% VE on the dyno. I'm not familiar with the cubic inch of your engine. Alot depends on that and the rpm you run it to. Being a nitrous motor I don't know that the manifold is a problem.