Drop the oil pan and inspect EVERY bearing- - - -rods and mains. Suddenly getting tight enough to refuse to crank when hot is a HUGE red flag. The engine might be salvageable right now. One more startup and a little tinkering, and you're going to have a boat anchor. I never trust a stale "rebuild", even if it was done by one of the guys I've trained. Until I personally establish that an engine has the proper clearances, I just assume everything has been done just a little bit wrong!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!