I think some of you need to realise that the aim of this project is to build a new AMIGA computer.
First of all ask yourselves what is the hardware best known for the AMIGA computer? It is a machine using custom chips based on Motorola 68k series processors.
That was years ago you might say.
Well ask yourselves what is the next natural step up from the 68k family? It is the PPC range of processors.
So just like AAA was going to be the next step up from AGA, the Amiga 6000 will be next proper step up from the Amiga 4000, equipped with the next natural processor; the PPC.
I don't see why the PPC should be a 600MHz G3.
For starters, when you are involved with the Apple Community like me, you realise that Amiga is still a fair bit behind, even with the likes of AmigaOne.
With the G5 now released, the G3 only has a short bit of life ahead of it before G4 is the new low end processor and G5 for everything else. I think some sort of G4 would be a good low end spec, say for example, an 800MHz G4? Maybe 1GHz.. as it will take time for it to be made and released, by which time a 600MHz G3 will be an antique near enough.