Depends on the C4. 88-up would be the direction you're looking for. 88-up Z51's got the 13" frt brakes and better rear end. 89-up got the ZF6 6-spd. T-5, T-56, SBC Gen 1, LS swaps.... the door is wide open on what's available. You can build a 400hp torque monster L98, or you can go with a higher revving LS-swap making 600hp.
The chassis isn't as good as the C5/6's, the handling can be improved. But keep in mind that the newest C4 is 15 years old.

