I have a foot in both camps on this one. If its largely original after 70 years I like to keep it that way and perhaps even correct the few bits that are wrong, but if, like both my current bikes, its been heavily messed with in the past, then I prefer to get it to be the best working bike withing sensible limits.
My A10 began its life as a Golden Flash but some time in the 80 or 90's someone decided to make it onto a Road Rocket, later another owner tried to turn it into an RGS, it last ran in 2006 and the RGS owner had no idea what they were doing.
So the Monoblock is long gone, I junked the Concentric 626 and fitted a 930 and I'm aiming for a good working Golden Flash / Road Rocket mash up. The world doesn't need anymore RGS knock offs and taking it back to original would be too much work, and why take off the ally head, TLS front brake and 4 spring clutch?