I have recently done this to a 216 that was sitting for 12yrs. The engine would not turn over , I found that the valves were stuck. I decided in the end to pull the head and sort the valves. The issue was old fuel had varnished up in the stems, it cleaned off easy on the wire wheel and fresh oil made everything flow easy.
I would use fresh oil .
I would pull the distributor and prime the oil system.
I would spin the engine on the starter for a few revolutions to make sure all is working smoothly .
I would then add fuel and spark and go for it.
This is what I did on my spare 216 and its a great runner now.
