Geeze, you guys make me feel old...hehehe.. I have SOCKS older than those shells..Hehehehe..
It really depends on how the ammo was stored, but unless they were exposed to REALLY extreme conditions of heat, cold, dampness. etc. any plastic shot shells should be fine..There is no safety issue.... Go ahead and shoot them... The worst you might get is a misfire..They are not going to blow up in your face.
Paper shells are somewhat less weatherproof, but if they have been stored in fairly dry temperate conditions they hold up pretty well too.. I love paper shotshells ( they remind me of my youth) and have shot quite a few over the years, some dating back into the 1920s... I have had a few duds, but most them went BANG just like modern shells, and lo and behold, they still KILL stuff just like modern shells..
Shoot 'em and enjoy 'em...
I can remember when Remington introduced the first plastic shotshells in the early 1960s..In fact, I have an accumulation ( rather than a collection) of vintage ammo, and I have a few of Remington's first plastic shells...One piece plastic wads had not been developed yet...They are in a fairly transparent green plastic casing and you can see the shot, the fiber wad and the powder.. It was pretty cool stuff back in those days..