Mark is correct. The best way to store an engine is with the fuel system completely dry. This is the way they were shipped and stored when new. When I had my tool rental business, equipment such as pumps and generators were stored with dry carburetors, as the time of next use was uncertain. Equipment that was no longer used was stored completely dry with some oil added to the cylinder and the engine stored on top of the compression stroke. This kept moisture out of the engine and reduced the chance of stuck valves. Engines stored like this would fire right up even after sitting idle for years.