I have not seen a G98 with a PwB marking, I suspect it is possible but it would be unusual. I went through my Amberg files looking for this rifle but no luck. It's too late to run down the auction, but it would make a good discussion if we could see pictures of the rifle.
I also looked up CB remarks on the subject, he stated only Kar.98a are known so far as rifles go, but left the possibility that G98 could exist. If so an Amberg sure seems the most probable. Too bad you couldn't score it, but the fact remains that anything police marked carries a premium, there are several specialists running that angle and they aren't scared to pay a premium.