I had a '65 Rustang that I installed a Global West suspension kit on.
It necessitated removing the front upper A-arms and drilling new
boltholes to relocate the arms higher up in the vehicle. The kit came
wth new rear leaf springs. It was VERY stiff, and very low, but
handled great. Although the ride was firm, I wouldn't characterize it
as uncomfortable; maybe because it was controlled and not bouncy.