Not mentioned but do you add a bottle of zinc additive to your oil or do you use a high zinc oil to start with? They reduced the level of zinc to help the catalytic converters live longer years back and that kills an engine with flat tappets. Especially a high lift with lots of spring pressure. I use the Lucas and there are others also.
https://lucasoil.com/products/engine-builder-lubricants/engine-break-in-oil-additive-tb-zinc-plus
You can hash out which oil is best forever but most any oil works just needs the zinc added for the older engines.
As far as sitting inside the engine. I just this year pulled the engine out of my 73 Mach 1 when cleaning it up to go to museum. I pulled the oil pan and there was no water. There was no rust, when I pulled a rod bearing it still had oil in it. I pulled valve cover and no rust and no stuck valves. This cars sat for 37 years on a dirt floor in open pole barn in a very humid climate, over 100 inches of rain last year. I put new gasket on oil pan a put back on. I put my normal Havoline oil in and the zinc additive and the engine fired right up and no issues. If the engine is closed with air cleaner on and no way for mice to get in through exhaust you should have no issue with a car sitting. I actually sent sample of oil for testing and came back with no moisture just high level of lead due to leaded gas back 37 years ago.
