Further to this story, I was asked by the owner if I would rebuild his engine to which I agreed.
I stripped it down and inspected everything.
Amazingly the sludge from the followers did not wear anything out but it was caked heavily on the inner perimeter of the flywheel and had almost blocked the sludge trap.
There was no sign of wear on the big end journals, still on size from the grind and the camshaft was also in good nick.
The sludge was not easy to remove, it would not wash off in the tub without brushing but I am hopeful that it is all gone.
The crankcases are very early, dated January 1950 and do not have the oil feed to the cam trough and timing gears. I am curious as to when the oil feed was introduced.
There was a heavy deposit of carbon on the piston crowns and evidence of oil passing the Hepolite rings. I had the barrel coarsely honed and was informed by the machinist that the barrel had about 0.002 ovality and was a bit bell shaped, possibly caused by over heating.
The next problem was the valve adjusters, new when the engine was overhauled but worn out in 500 miles. They are very soft, I dressed them with a file and polished them, will try to harden them in the future.
I changed them for a used set I had to hand.
There were two left hand rods fitted to the engine so I blocked the oil hole on the one on the right.
The job is finished and the engine has gone home. Just waiting for the report on it when is back on the road.