There is a sheet metal cover at the underside of the bellhousing that can be removed to expose the lower 1/3 of the flywheel, and the clutch/pressure plate assembly. It's also a convenient place to use the straight end of a medium-sized shepherd's crook wrecking bar in the flywheel teeth to turn the engine back and forth. Just wedge the bar into a tooth and use the edge of the bellhousing for a fulcrum. If (or when) the engine gets hard to turn, reverse directions. A few ounces of a penetrating oil like Liquid Wrench or KROIL in each cylinder before you start turning is a really good idea, as is a good soaking of the valve springs and valve guides a day or two before the engine-turning effort begins.

www.kanolabs.com

This stuff is the world's best at loosening up a rusty engine.

No matter how dry the storage area, the cylinders that had valves partially open when the engine was stopped will rust due to humid air finding its way in and out of the engine due to temperature changes. It's highly unlikely the clutch has anything at all to do with the engine's refusal to turn. Unless it breaks loose pretty easily, count on doing a teardown and rebuild.
Jerry

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