OK... So here's an update.
Aircraft has been sitting for a little while now, and new leakdowns tested on a stone cold engine. Results were 77/80 78/80 78/80 78/80
Leakdowns don't lie.
So I am happy to continue on as normal. The leakdowns, colour of the oil (still looks new), no oil use and colour of the plugs confirms that the motor is fine.