I definitely agree that whoever owned it previously didn't know what they had. I don't think the white is powder coating as when I started inspecting, I was able to peel a large flake off the dropouts.

I have taken the BB and seatpost measurements with a caliper. I'll admit, I'm rusty and was never great to start with. I plan on stripping frame this weekend and we'll see if that uncovers some additional details: chrome bits, if seatpost is stamped, any markings on the fork steerer etc.