Julian,
Well now that others have chimed in recommending I stay with the RGS front hub - who knew that was on the bike??, and the rear QD hub (A7 or A65??) resulting in better breaking both wheels now won't be stock so why not venture off into an interpretation of what BSA would have done with a bike at the end of the assembly line where someone wanted to try out some interesting leftover BSA parts?
I have done the same thing with the 40 year-old electric garden tractors I restore. Found and installed lots of NOS and optional parts to upgrade/modernize them. Still look and drive stock - just better charging, electronic control vs the wicked pesky circuit boards, electric drive & lift motor upgrades, new gauges & switches, slightly oversize tires, beefier steering, etc. i will be mounting as a canopy a 240w solar module on one tractor for trickle battery charging after mowing the lawn. www-watts-up-elec-traks.com.
Thanks,
Steve