Rebuilt 904, no 3rd gear???

Good deal Mopardude! No it doesn't have to be adjusted perfectly. Any time it's shifting good and firm your ok. When you install a shift kit it raises the pressure and that greatly reduces the possibility of damaging the trans. if not adjusted right. Does your valve body have the part throttle kickdown module (generally all 71 and newer have it)? If not you may have trouble getting it to kickdown on it's own cause the shift kit raises pressures accross the board which seems to reduce kickdown.