Sounds like nice progress on that engine ,, I like the wee 216 , you can get great economy from it .
When I was working on Aircraft engines , P+W 1830 , etc, the proceedure was to run the engine in , do all the tests , drain the fuel out , inhibit the bores with a sprayed on waxy substance , fit the plugs back in , varnish the whole exterior of the engine and send it off to the stores .
The engine would be re-inhibited every 5 years , that involved pulling the plugs , turning over a couple of revolutions , and spraying more waxy preservative inside it and reinstalling the plugs .
Sometimes the engine might not be used for 20 years ! imagine the inch of wax on top of the pistons
. When the engine was taken out of long term storage , it was stripped , cleaned and reassembled , retested , then approved for service . The airforce was a world unto it's self.
I am sure you dont need to go to those pedantic measures , I have had a 216 in storage for 6 years , just with a good spraying of oil down the bores and around the valves , it was reserrected a little while ago , fitted new plugs , fresh fuel in the carb ,,,,,, lovely runner .
Oh , yeah , valve springs take a set ??? only if they are faulty . Those 20 year storage engines were fine .