Mystery film identified, and it's not bad!
Just in case any of you remembered my dilemma about two months ago, when I bought a darkroom setup from somebody, and part of the loot was about a dozen rolls of unidentified film, (bulk loaded by the guy), and you're curious, I just developed the test roll. (I would have done it sooner but my wife and I were on a two month road trip.
We're back home in France and I'm developing every day to get caught up on the twenty-something rolls I shot on the trip. With some advice from ever-helpful APUG members, the best guess was Plus-X 125, and that's what it turned out to be. It had sat in a bag, in the corner of his basement for about 12 years. A lot of them weren't even in cans. I generally shoot one stop over, but because of the age, shot it at 32, one roll only, and developed it in HC-110 along with some normal rolls of FP4. Same speed films, but the mystery roll shot at 32 instead of 64 would give me that one extra stop.
When the film was taken off the reels and hung up, the roll of Plus-X was hanging between two fresh FP4's, and there was an obvious difference, but considering the age and the terrible storage, I'm amazed at how good it is. Definitely usable negatives. Once I print at least a contact sheet, I can use the rest for subjects that suit the slightly reduced contrast. The increase in the base fog looks minimal, just a little less contrast.
There was also a bunch of various papers, about 250 sheets in all, and I'm hoping it's also in decent shape. Maybe good enough for contact sheets, etc. anyway. I guess his basement might have stayed fairly cold.
Nothing like a pleasant surprise now and then.