Hey. I'm in the process of converting an 84 Ross Gran Tour II into a fixed gear. This is my first build. I got the frame bare (and free) so there is no older parts to compare but I need to know what size the BB is. I know I need it to be 107mm in length but what I don't know is the thread size. I went to Sheldon Brown and I think I need a 63mm but I'm not sure. Any help would be great.