You do not want to use shims under a shaft that has a roller cam operating it, but you can clearance the rocker if it's not much. IMO, you should step up to a real race rocker system from T&D. The .650 lift... is that with 1.5s or the 1.6s? Why run 1.6s and not put the rate of lift in the cam? 1.6s need more room for pushrods, and the springs and lifters will be worked even harder too. Cranes are good to about 420lbs open before you should be concerned with life span and breakage. You have plenty of room for retainer to guide.
