An old trick for freeing a stuck engine was to pour brake fluid through the plug holes and let it sit for a day and repeat for a couple more days. A gentler approach than dumping the clutch and often would save an engine. Another old trick on running engines, was to mix a little tranie fluid in the gas tank to help clean out carbon deposits.
I have left alot of engine's sit for long periods. What I've usually do is take the coil wire of and turn it over until oil pressure is up or until I think it should be. I once found ford a 302 Ho that was sitting in a old ford ltd for like 8 years , ripped it out and stuffed it into my 78 bronco with fresh oil etc. Turned it over for a bit hooked up the coil. It flashed up and I ran it for years in the bronco... but did I cause extra wear and tear?? I think priming the engine is a hell of a good deal for any motor.
