valiant driver suspension

You've got some good parts. Go with the circle track rear springs and the largest torsion bars you have with the '73 k-member and sway bar along with the '73 disc brakes. It would be a good idea to build a big bolt 8-3/4. For handling keep the rear springs in the stock location. Go with good 60-series 15" radials that fit the car (215 or 225).