Possibly some might like a look inside the timing cover.  What you see here are vernier sprockets for both the camshaft and magneto.  These work on the vernier principle, where the outer sprocket has a certain  number of locating holes in it, on the same hole circle diameter as the hub beneath, but differing in number by having one more hole than the hub.  Only one pair of holes line up at a time, which gives a possible number of combinations equal to the product of the two numbers multiplied by each other.  This is shown clearly in the large image of the magneto sprocket detail.   Behind and  left of the camshaft sprocket there has been extensive welding done (also outside) on the crankcase so that a one-off quick-change cam bush housing could be fitted.

We used a bronze alloy bushing, not being enthusiastic about a needle roller conversion.  This required a large diameter housing for the bushing which in turn necessitated a considerable amount of  welding both inside and outside the crankcase on the timing side so the bushing housing would have somewhere to go.  This is clearly visible in the large version of the second image shown here.

Additionaly, this crankcase (P-11 in origin) had been severely damaged prior to our purchase.  A  major area   where the magneto bolts on was busted off and missing.   A replacement was rough milled and welded in place. 

The mating joint of the crankcases survived all this welding, but there was no chance of supposing the cam bushing bores could be  concentric or on an axis parallel to the crankshaft.  So it was time to blueprint the crankcase.  A crankshaft mandrel was made so that an axis could be picked up off  that to true up the cylinder deck in relation to it.  It also provided an axis from which to  bore the camshaft bushings, backing out from the blind ended drive side bushing, boring both bushings in the same pass. The magneto area of the timing chest also got cleaned up.  This is just the high points, the details were more complicated.