Here is a picture of two bellhousings. The single wing is for a small 157 tooth flywheel, and uses different bolts to the transaxle. The double wing bellhousing says De Tomaso on the casting, and is for a large flywheel and has bolts on the bottom for the starter plate.
I may have heard a long time ago that somebody in the US cast some repro bellhousings, but I have no idea if this is one. The quality of the single wing is poorer than the double wing.
Jay