Thanks chaps!
I assembled the engine last year, after a two year lay-up after a crash (not too bad, but cosmetically damaging for the bike). The roller bearing outer cage sat very loose in the case, but I bodged it in place, with punch marks and loctite. It had no play, but could be pushed out with ease. The timing side bush was fine. I spent many attempts to get the end play correct, and do not doubt it at this point. At speed there is no weird noises, and the rockers emit a monotonous zizzle. But at idle I might hear something like piston slap, though they were fine, and only have about 4000 miles on them, fitted in freshly bored barrels. I will try the peg trick, if I can find enough wooden ones :) Maybe also a round of tightening everything... Maybe I should try to make a video at speed.
Otto in DK