I'm such an idiot ! I just had the bottom bracket in my hand, as I was transferring everything to a new frame, and I completely forget to measure the damn thing !!!!
As I suspected, it's some funky off-brand I'm not familiar with, and I'd been considering installing a Shimano UN55 ($20 or so is worth the peace of mind), so I've been wondering what size it would be. It's a 68mm English thread, I just don't know what the spindle length would be for a single speed crank, and figure somebody here is gonna know.
edit: I've been searching the question, and the answer seems to be, "it depends". But I just measured it (externally), estimating where the spindles ended inside the cranks, came up with something around 4.5", which is about 114mm, and the Shimanos come in a 113 and 115mm. So i guess I can yank the cranks again and get an exact measurement, or just wing it, figuring a mm either way shouldn't make much difference!!