I thought more people might reply, but they didn't, so....
The easiest thing to do is to put the Hoosier bias ply on the car as it sits, assuming it was set up correctly with the Goodyear bias ply tires which are no longer available. The set-up should be similar in terms of camber, spring rates and probably tire pressures from what I have seen. I assume that your Dad ran 8 x 20 x 13 Goodyears.
However, a case could be made for making the switch to radials, since you aren't used to anything at this point. There is enough information out there to allow you to come pretty close in terms of initial set-up, and the new S 80 series radials have been shown to not only work, but to be actually faster than the bias ply tires even on a live axel rear. Many teams have already shown this to be the case, myself included.
If I was you I would contact Brian Linn who just recently put a Lotus 7 on the pole at the Runoffs at MRLS and is usually very free with information for fellow competitors. Craig Chima would be another source. Also Jerry Hinkle, Rob Futcher, Austin Britton, Peter Morton, and Gary Johnson if you know any of these folks. I think that all of these people run the bias ply tires.
If you want some info on the Hoosier radials on a RWD live axle car send me a PM.