>>> Perhaps MOS can boot with the MacPro bios?

>> With cards without PPC ROM, MorphOS needs AtomBIOS, which those cards
>> don't have AFAIK. "MacPro bios" seems to be yet another type of BIOS/ROM.

> Does it matter if it's PCIe, PCI or AGP?

AFAIK, there are no PCI or AGP cards with "MacPro bios", so that BIOS type should only be relevant for PCIe cards.