The aerospeed bearings are tiny, it was said it was to keep the weight down. I think they are the same inner dia as most cranks (19ish mm) but the outer dia was only a few mm more than that. One of the bearings from my set was totally locked up. I gave it to a bearing supplier and he found a replacement but it was mega expencive so I didnt get one. Maybe well worth it to make a set of aerospeeds complete. A few years later I asked him for the bearing number but he forgot it, and had chucked out the cup and mashed bearing I had given him!!!!
As ususal ... I am no OS help at all. Sorry! If you have the OD and the ID of the bearing you should be able to get one, but they aint easy to find. Give me the size and I will have a go if you want.