Hi Steamgen,
To my knowledge, there are no references in the code to age of equipment. As far as condition, though, there are operational requirements for testing by a qualified company on a periodic (annual) basis for certification, and a qualified company should be able to point out things that might need replacing as the equipment ages. Most pumps are renewable, as long as the case is intact -- bearings, couplings, seals, etc..., might need service periodically but the prime mover usually is a long-term animal. I have worked with pumps over 50 years old that were in fine shape. You might need to have the controls upgraded to meet the latest codes too, though.
I would recommend having the pumps inspected and tested by a manufacturer-certified technician. Since they don't run that often, I would bet that they give them a thumbs up for use.
Let's see if anyone else has an opinion too --
Good luck with your project, sounds fun!
Old Dave