Blimey - two posts in one day. Must have been a busy weekend. Split the cases again and carefully measured the crank using the more traditional method (sturdy straight edge across the cases, and measure to the bearing).
It soon became clear that with no gasket in the cases, the crank on its own with no shim would provide a preload. I previously measured endfloat by closing the cases with no shims, then levering the crank - I now suspect that I was using too much force, and what I was really measuring there was flex in the cases (!)
So - removing all shims from the crank, and refitting the case, the crank now spins freely, with a slight drag, and no measurable endfloat (without using excessive force...)
I also took the opportunity to double-check the big-end clearance with Plastigauge by fitting new shells with the old conrod bolts - all good with almost exactly 0.002" (0.05mm) clearance.
Next episode, assuming all goes to plan, I'll be carrying out the final fit of the conrods to the crank with new bolts, gooping up the cases with 3bond, and closing them.
