Pöllmann do make great instruments to have for vacant's at a concert hall. Every Pöllmann is pretty much exactly the same in feel and sound. They are tanks and they won't be sounding bad.
In my opinion, they won't sound GREAT either. They are as we in sweden say, "lagom".
Nothing dissapointing and nothing excitingly good.
There are exceptions, though. I've heard that Pöllmans from the 60's era (which concerns you) have a few wonderful instruments.
Many great players work on Pöllmanns, so you will definitely be able to play good music on a Pöllmann.
Don't choose anything by brand!
"Music is of course never important - it's made for pleasure!" says Anner Bylsma with a huge smile on his face!