That's a great write up and quite a story. What's amazing to me is that 1940 really isn't that long ago and they were still flying planes [military no less] as archaic as these..! The world's economic melt down and gradual recovery must have put a damper on progress. Governments used to stick to their budgets better than today I'll wager..
1940..most car engines didn't have oil pumps or pressurized oil systems. They relied on crank splash. The con rods had "ladles" that scooped up oil and flung it. Does your plane's engine have an oil pump..?
The old car engines used rubberized rope for the main bearing seals and the babbit bearings were poured in place, allowed to cool, then the mechanic would scrape the surface of each bearing with a draw knife until it was just loose enough for the parts to turn. Model A Ford engines were scheduled for rings, valves and bearings every 10,000 miles. By 1940 I'm not sure what the service interval had improved to, but I'll guess that 50,000 miles was considered doing pretty good. Blocks and heads used to crack a lot more often back then, too. Finding people today capable of properly working with the old mechanicals would be tough but thankfully they had some excellent shop manuals that show in great detail how some things were done.
I'll bet shop manuals for your plane would be extremely expensive