It sounds like you want a hot rod crate motor, but an I6. I don't know of any sources for that,although as Frank says, Jim Carter and others have rebuilt stock motors.
If you want a hotrod motor that's already built, then it would be much easier to get a 350 V8 crate from GM or other source.
However, if you wanna stick with the 6, then your choices are a little more limited...mainly to stock builds, rather than performance motors.
Another alternative is to have a motor built locally. Find out who build motors for the local racers and see how much he'd charge you to build up a wonna the Jimmy motors Frank suggests. Can't hurt to ask.
My preference is to build my own motors, but there are a lotta guys who run crates or speed-shop-built motors and are real happy with them.
