You really should replace the clutch release (throwout) bearing and the pilot bushing as well. They are inexpensive and there is no reason to risk a later failure just to save twenty or thirty bucks. What's your time worth to have to split the tractor again if one of them fails? How are the clutch fingers? Any visible wear or scoring on the contact ends where they meet the throwout bearing? I suggest using blue Loctite on the bolts when reassembling the clutch, flywheel, bell housing, etc. Don't use the red Loctite. Torque to book specs unless Tommy recommends something different. If you're going to set up the clutch pack on the bench, you need to bolt it to a flat reference surface. In order to get the clearances set correctly, the clutch pack must be compressed just as though it would be in the tractor. I'm unsure what you mean by "gap spacers" - do you mean thickness (feeler) gauges? Sears has good ones, yes.