I have a 1977 Chevy step-side. originally a fleetside. the enigine was a 305 trans with 350 auto. stock trans would have been a 400. must have been switched at some point for a 350. Engine went south and I decided to make it a project and get a stepside bed and get a new engine.
Bought a 1978 corvette motor off a neighbor and had it rebuilt. 350 4 bolt main.
truck runs great but hit the gas and it just doesnt take off, tires wont spin,with not much weight on the rear you would think it would light up the tires. Once I hit second gear it takes off like a scolded dog and hit third gear forget it its gone and hold on.

What gives any suggestions??
Paul