i don't know a lot about this kind of stuff but is this throttle body conversion similar to what your talking about. the small photo of the underside of the throttle body there is some metal cut away. just ignore me if its not. (might have to register to view it) http://www.twincam.info/index.php?showtopic=42350
register on twincam.info and you will find everything your after. there is heaps of info and i will guarantee you'll find what your after even an engine if you don't already have. bigport and smallport is really up to you everyone has there own opinions on the 2 but i would think a smallport would be better for what your after.