Kz650-C3 and Kz750-E2 bottom case compatibility?

I noticed I'm missing a chunk at the bottom of the case by the ignition. Not thrilled about buying another bottom case and was wondering if the bottom case out of the Kz750-E2 engine I have lying around might be compatible. I know the oil pans swap over pretty freely and a lot of other parts are the same or similar.

If nobody knows for sure I'll tear it apart today and examine.

Got the 750 bottom off, need to compare still. Looks possible so far.

They are machined as one unit.
Could you use a piece off a junk case and have it welded in?

Thanks, that answers my question. I'll have to locate a welder who can fix it for me. Thanks!

Yeah you really need matching cases.