What to do before shooting a shotgun that hasn't been shot in 50+ years

Welcome to SGW, both guns are considered modern firearms built after 1950, unless you see physical damage or rust pitting I would disassemble and do a normal clean and lube then take them out and break some clays, I would not shoot steel shot through either gun but there are other options if not toxic shot is required where you shoot.

Additionally concerning steel shot. If they are nitro-proofed you should be able to use standard steel shot, not high performance steel.
Pigeonwatch forum.
BASC.

Old gun oil can get gummy. I’d clean with something like Gun Scrubber which is basically carburetor cleaner. Blow out with compressed air. Re lube with break free or whatever lubricant you prefer. Check all barrels for any obstructions and run a brush through them while you’re at it.

Clean oil and shoot.

If low on GunScrubber, I use 91% Isopropl alcohol

If the barrel chokes on the guns are full, they are not OK for use with steel. Mod or IC OK with steel. LOther wise they should be good to go after an inspection and cleaning.

Thanks everyone for the replies!!

All good advice, take them down as far as you can or feel comfortable going, clean and lube them well. Put them back together. Go buy a couple of snap caps and put a piece of tape or sticker on the primer and see if your firing pins make contact or pierce the paper.