Thanks for the replies! I'm planning to use the bottom bracket and the headset as well, as long as it will work. Maybe I will put another crank on it, but so far the moving parts still work ok. In the meantime I acquired another frame, with less oxidation, and I plan to use this one for a build first, but I will strip the paint of the more damaged one later and inspect the frame. Since I don't have any electrical tools at my current place for grinding and sanding it will have to wait some time, but sanding by hand I noticed it's best to do the whole frame and not only the parts that look affected in the first place.