You're in the same boat we michigander's were last year at this time. We ended up with a dart based 427w and an SPF, both out of Ross, Ohio. We couldn't be more happy with the car and the engine. Here is our engine builder's info if you're interested in another, possibly closer, option:
Eric at Performance Engineering
2681 Morgan Lane
Ross OH, 45013
513 738 5001
pecobra@aol.com
If you do end up contacting Eric, tell him Paul from Grand Haven sent you. Convieniently, the SPF dealer is right next door, but I don't have their contact info handy. Eric could probobly give you the number. Check my homepage for a ton of info on our build if you're interested.