Nice work. I haven't begun to explore my #50 yet. Your pictures of the boiler and heater set up are helpful if I ever have to go into mine. I've slowly discovered cleaning is a trial and error process. Luckily, I think a little soap and hot water will probably be all mine needs.
I think your engine would benefit from a total restoration. After all it's obviously been used and then neglected for so long it deserves a bright future! Good luck.