Hey Planeclothes, I don't know who put you on oven cleaner, but I wouldn't take any more advice from that source!
You might try a method I discovered while watching an old Model Sport Magazine Video (Vol 1 Number 1). The method described involves the use of antifreeze in a crock pot or slow cooker. You know, the one your wife hasn't used in the last 4 or 5 years. Buy the cheapest antifreeze you can at the auto parts store. any brand, it doesn't matter. Pour enough antifreeze to cover whatever part you are cleaning, into that old crock pot and turn on high. You can do as little disassembly of your engine as removal of the glow plug and back plate, but at least that much to be able to thoroughly rinse the engine after 'cooking'. Place the engine into the crock pot, (very carefully if already hot) and leave for 8 - 10 hours, covered. Doing this outside is best but inside is ok in an area where some outside ventilation is present. Hot antifreeze has an unpleasant smell but the fumes are not leathal. (Garage or Basement with open window or door) Remove the engine or parts with tongs or long nose pliers and place directly into a bowl, pot or bucket containing luke warm water and a dab of diswashing liquid. (this will allow the part to cool enough for handling) For stubborn extremely bad stains use a stainless steel brush to gently remove. It won't take but a gentle scrub for even the worse stains. If you want to make the engine look like new, go over the entire surface with 000 steel wool to polish. Finally thoroughly rinse in clear water and either lay aside or blow dry. Lastly, be sure to oil the engine internally and reassemble.
I have used this method on 4 different engines both 2 & 4 cycle that had been 'in storage' for 15 to 20 years and the results were terrific. This sounds like a lot of labor and trouble, but then what is you goal? The beauty part is that you can reuse the antifreeze over and over, it is not caustic and will not damage your aluminum or steel engine parts. The only dangers are "hot antifreeze will cause severe burns if not handled carefully, and don't leave the crock pot to cool off in an area where curious pets or children can get at it. It is poisonous if ingested!!!!!!!! I'm not sure this will work on an engine already exposed to oven cleaner, but if it doesn't it will be a possible method for you to use on other engines in the future. Good luck!