Would this be a bad time to say that I'm looking for a set of main bearings, black or blue, also in RSA? 
Yup, if I don't come right, it looks like this will be my only option..Why not to produce (bronce) main bearings like these ( ? )
View attachment 6682
These are used for BSA 650 etc.
Produced with an undersize, so you can grind the crank and have to customize the bushes/bearings for the correct size.
The bushes must be installed into the crank house to get the right/correct angle for the crank and rods.