Hi, Quick Cal!
Just read your post on the free Craftsman Table Saw. What a coincidence. I just purchased the '94 Version of this same saw along with several other pieces of equip. I am putting together a new shop in my new get-away place in No. California. I was lucky enough to find the 3HP version with a Biesemeyer(Delta) upgraded fence. From the research I did before my purchase, I did learn that the Delta fence is one of the better upgrades for this Craftsman.
Have you started up the motor yet? If not, you might want to very closely inspect the motor mounting bracket. I did some research and apparently on some of the 3-HP models(not exactly sure which years but definitely 80s - 90s) the motor mounting bracket used by Craftsman was not quite up to the task! Specifically the mount was bending too easily(probably during belt tensioning/adjusting) which occasionally led to the motor shaft getting un-parallel to the blade arbor shaft, and THAT led to the two pulleys getting out of alignment. The poor alignment syndrome apparently led some users with loose/poor condition pulleys to having the motor pulley come flying off of the motor shaft . OOPS! ONLY reason I mention this is that your specific circumstance (no motor yet mounted, I think?) MAY be the perfect opportunity for you to check this out and maybe re-evaluate things, i.e., Do you STILL want to assemble this sucker and spend money upgrading OR (and I have NO idea how much work is required to replace the motor mount) in your case, IF the inside of the unused motor has issues, do you even want to risk chasing good money after bad? I PROMISE, I'm NOT trying to rain on your parade of apparent good fortune in being given a basically unused 20 year-old 3HP table saw. Just trying to save you some potential aggravation, some of which I, too, may be facing!
That said, If you do go forward with the final assembly and upgrade. Maybe we can help each other with the info learned.
Any way, GOOD LUCK with the rust removal and final re-assembly! (Naval Jelly & lots of 00/000 steel wool maybe? )
I'll watch the forum for your progress if you decide to share it!
best, Stan ("Brookeville")