The first question is why you think the engine needs work. You mentioned it overheated. Is there oil in the cooling system? Exhaust smoke? Reduced power? Engine will not turn? Are you able to check compression?

Your plan to fix the engine should be based on what you believe is the problem. I wouldn't remove the engine to replace a cylinder head gasket in a passenger car. I don't know how the engine is situated in a van, though.

Sixto
87 300D