Nice to see I am not the only Mac-emulating 68k Amiga-User here. To make it run, you can either deactivate superscalar mode of 68060 (can easily be done from within Fusion and I think it's even deactivated by default on latest Version of ShapeShifter) or you can buy a newer 68060 (i.e. Rev E41J), because the newer version doesn't have that bug anymore (I have it and it works just fine with Fusion, OS8.1 and Superscalar enabled).

By the way: There NEVER has been a 68050, as far as I know.