My 46 has 2.5" MoorDrop I beam, plus factory sway bar and good tube shocks with radial tires really handles well. An even fatter sway bar would be a plus as well. Also the 42-46 truck steering box will swap in the 40 with modern ball workings.
Bill S. how did you convert to roller bearings and do you have part numbers or a source for a kit? I'm still six lug with stock artillery wheels, would like to go disc brakes but stock rims wont clear.