I hope this is not too late for you, but I just completed my install. 1971 GMC Stepside with the ridetec coil over. I did have some issues due to frame twist, but took my time and a bit on the alignment machine, but it dialed in great.
I installed the rack and pinion from No Limit Engineering at the same time as well as 255/55/17s (8" wheels) up front and 175/60/17s (9.5" Wheels) in back. Hope this helps. Drives like a new truck!