A tight engine will crank without issues. In addition to heat and timing, another thing to keep in mind is other-than-ACDelco rebuilt starters.
Megastarters notwithstanding, if you don't have a new--not rebuilt--ACDelco starter, get a rebuilt built by ACDelco. The problem is the armature. Other rebuilders set their own specks for turning down armatures, the thinner the armature, the less cranking power. ACDelco has specks that it follows, and if the armature doesn't speck-out, it's crapped-canned.
