[SCadaddle]

Disclaimer: I'm certainly no certified engine builder but I did assist in rebuilding the top end of my 82 SC. That being said,

At a minimum, I would replace the O rings around the engine case "through bolts"---the ones with the bolt head on one side and the acorn nuts on the other one at a time due to the use of heat with the torch to remove the lower head studs in such close proximity to those bolts and acorn nuts, and do not just loosen the acorn nut and pull the stud through the case before you use something like a dental pick to remove the old O ring on the acorn nut side----you don't want to pull that old O ring into the case while it is still on the bolt.