these motors have pressed in valve guides (a lot of pressure when they get old) where the next generation motors were like small block chevy V8s and intregally cast) you will need a special stepped tool to press it out (can be made easily on a lathe). If not much is missing maybe leave it alone as head must be removed to get guide pressed out. It would probably take an old automotive machine shop to have a new replacement guide. Good luck, not a hard job, just be careful not to ruin a good head. Reread your post, 3/4" seems like a lot,pressing in a new guide would also mean probably retouching that valve's seat before remounting the head (...while its off...type thinking)
Last edited by edski; 12/29/10 03:00 PM.