Take the pan and valve cover off, roll it to the edge of the shop door, flip it upside down. get some Gunk engine cleaner and soak the inside of the engine from the valve cover area to the crankcase. Let it sit for about 30 minutes. Then rinse it out with a high pressure garden hose. Let it drip dry then blow it out with air. Spray the inside down with WD40 or some other penetrant. Put the pan and valve cover back on.
Now when you get ready to start it, you will want to disable the ignition and spin the engine over until the oil light goes out so you will reprime the engine. You will have washed a lot of the oil out and that will assure it does not fire up dry.