Hi Dinky . . .
Shims are not unusual:
But shims on just one side are . . . they are typically fitted in pairs.
Not sure why the previous builder decided to do that. It seems doubtful that any align boring was involved. More likely they didn't have a thin enough shim set so they opted for one side only.
I guess eccentric at the crown is eccentric . . .balanced or not . . . in this case the crown/crest is oblique to the cam side of the caps.
My understanding is that shims were designed to cope with minor differences in crank tolerances - not the basic machining of the block and caps.
regards,
stock49
