Speedmaster movement compatability

[Lifting]

Probably a very basic question but I have been searching around and cant quite find what I am looking for. What are the options with a Speedmaster date for new or better movements if the 7750 packs up, or i just want an upgrade. Will for example the original gen movement fit in there or a swiss 7750? I think I read that it is probably pretty difficult to get a swiss 7750 in, but is it a complete non-starter? Thanks

[whitestripes]

I'm under the impression that a Swiss 7750 will fit Asian7750s, but the hand hole sizes might be different...