which 833 for a body ?

You can put a B body tranny in it if it has both the front and rear mounting locations, I have seen plans on this site to build an adaptor bracket. The A body shifter mounts between the B and E body locations. You would have to shorten the drive shaft of course. A detail which may be more important is the gearing, you want the gears close together in ratio for a small block and further apart for the big block, since the big block has a wider torque curve.