.....I invested about £20 in a basic borescope that plugs in my phone and explored the combustion chambers via the spark plug holes..
You did well dissolving the oily/carbon build-up
The first "sports"car I owned, in 1971, was a 1959 Fairthorpe Electron Minor. Somebody else had built the kit (reasonably well) and had maintained the mechanicals (reasonably badly). On a number of occasions it took me and my girlfriend at the time, from W.London to Cornwall. But it was real heap; I kept the exhaust valves (from a Standard Ten) as a souvenir.
P.S. She married me anyhow, and now puts up with me and the Morgan.
Peter 2009 3-litre Roadster "Ivor", royal ivory / green