Wow, your dad just dove right in, didn't he?
I'm not as sure about Windsors, but Lima engines do just what Myrl said.
The O-ring on the stem dries out and the stem of the distributor gets corroded.
The iron of the block isn't going anywhere....
I've resorted to torching it until spit sizzles and drenching the base in ATF.
Even then I've had to work them loose with a big pipe wrench.
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.