cb400bill The best I can do at the moment is this. It's dark here now so it'll be until tomorrow until I can take a picture of the whole frame.

I've also uploaded a picture to that with some BB related stuff that the seller gave me with the frame, but it's quite incomplete and I don't know if it helps much.

Pictures: add /a/whGMM99 to imgur domain

Luckily I'll be able to post pictures soon at this pace haha.

nlerner Thank you for linking that, that seems like the most promising solution at the moment. I'll have to look around a bit because the cheapest one I can find in Japan is a whopping 160 USD. I'm sure there is a similar cheaper bottom bracket I can find here.