You should be able to pick up a rebuildable core at most wrecking yards. As for gas mileage, I actually got the very best mileage out of a large venturi monojet, but the Holley/Weber 2 barrell gives me the best all around performance, cold starting, and drivability.

Boo Radley

Paint it black with a rattle can, and drive it like ya stole it!