engine swap question

Torsion bars are available from Summit, Mancini, etc.. Rears are 8 1/4 or an 8 3/4, both A-body size, to bolt right in without alteration. 8 3/4 is beefier and more expensive. 8 1/4 is about half the price, and are said to be good for up to 400 street hp. There are other more expensive exotic rears available for racing duty.