I'd do a little spinning with the starter with the plugs removed, once you're sure there aren't any serious tight spots. Then check the compression "dry" followed by a wet test. Write the numbers down for future reference, and if you do decide to run the engine, repeat the tests after some run time.

I like to run a couple of quarts of Diesel fuel with a fresh fill of 30 weight oil, enough that the oil/solvent mixture is splashed all over inside the crankcase by the spinning crankshaft and rods dipping into the overfilled oil and solvent. It does a much better job of dislodging sludge and crud than hours of scrubbing with solvent and a brush. Just don't drive the vehicle or put any other type of load on the engine, A fast idle, maybe 1000-1200 rpm is plenty to get a good internal wash job. Quite often, an engine that seems to be beyond help comes back to life after a good running flush. If not, you've saved yourself a lot of scrubbing during a rebuild by loosening up the gunk.
Jerry

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