Any SBC will drop right in- 327,350,383,400-
The pulley / serpentine belt sytem is another matter and if you want to keep the FI.
Hell if it only for racing a Big Block chevy will fit nice and you could build the 700-r4 trans to take about 500 Hp.
Auto are quicker-more consistant times anyhow- And the rear axle's will last longer too !!
