First up was to check the timing and Valve clearances. These were found to be excissive, and further investigation reveiled the head of the tapet adjusting bolts had been filled, with epoxy type of filler ??

The concave surface ranged in depth from 0.009" to 0.017" - plus the disired Tapet clearance.
Interesting 0.015" inalal lift on the push rod was equal to 19° on the flywheel - for those followers who are mechincally minded you will see where this is going .......