Begs the question: Why would you want AOS4 on 68k? As we already have a 68K AmigaOS :-)
RS6000? You must be kidding. How many RS6000 users are out there, and how many of them will actually want to buy an AmigaOS?
Sure, if you want AmigaOS on your RS6000, just compile AROS for it :-D Thats why we make AROS, so you can run AmigaOS on hardware of your choice!!!