built a 408 small block. supercharger options?

The biggest problem I see right now is your static compression. It's to high. Preferably you want your static compression to be about 8 to 1. You can probably use the compression you have now if you run an intercooler but that is going to drive the cost way up. I would dare say you are looking at, at least $7000 to set it up with that compression. Sorry for the bad news. I don't have a supercharger myself, but have been trying to design a blower engine myself. Maybe somebody with one will chime in.

Jack