72 half ton rebuild questions

[Nightrider]

Trying to put my 1972 GMC back on the road, but not really sure how to set up the suspension. I used a 2/4 drop with only coils being cut in the past , but wasn't very happy with the performance at highway speed on bumpy/ choppy roads. Im planning on 18 inch rims in the future, running 15 now.. Driving on rough country roads or interstate hwy, hauling my ZX14r in back at times.
Should I just rebuild to stock dimensions or try 2.5 drop spindles with 1 inch drop front springs and deal with the leafs in back some way?? Thanks for input !