After ignoring it for a few months I decided I needed to get the damn thing sorted and sold. I dropped the engine out and stripped it and opened up another can of worms.

Although the bottom end sounded okay when it was running the main bearings had definitely seen better days and the r/h outer main bearing locating pin had sheared at some point and spun in the cases. Not only was the crank f****d it had trashed the cases when it had spun

Luckily I had a rebuilt crank with fresh main bearings and a set of cases in my rapidly diminishing spares stash. So engine back together with fresh crank, new seals through out and a leak down test showed it was all air tight