Just a quick note,
Junkers did diesel in WW2 so i believe, May be worth looking at detroit diesels, they are 2 strokes with poppet valves. Adapt design to small aircooled thumper. Also look at foden 2 stroke. Another diesel stroker that sounds fab! Am in worcestershire if you are in the area & fancy a natter about poss diesel stroker for aviation.
Merv!