The first one is closer to 1960, and from the looks of the ref evaporator coil it has a bad compressor or possibly a bad cold control, but if was a bad CC everything would be frozen solid in the FF section with that much frost on the evaporator.
Yeah, something is not right with the first one. That is like a week's worth of frost if not more, so I'm betting on a compressor that's straining to keep things cold. $500 will get you nothing but headaches.
The second one looks like a large size '58 Combo that requires defrosting. $200 isn't horrible, but it's not a deal either.