What exactly is stopping a PPC G3 accelerator being plugged into an Amiga PCI Bus Board. Sonnet do one Crescendo/7200 G3 that would be perfect, for about £135.
Maybe the fact that this card (compare the picture between "SharkPPC" and the Crescendo, they are identical, only the cooling part is different) doesn't know anything about the system it runs in.
So, the Amiga Classic part has to initialize it and give it access to mass storage for booting. Unfortunately, the Mediator (in the configuration it has been sold) doesn't support the needed PCI configuration method which is mandatory for PCI bridges like the ones used on Crescendo.
You can use two different mechanisms for selecting PCI slots during "autoconfiguration" on the PCI bus; one is limited to a single PCI segment and uses memory mapped decoding for the slot, the other one is based on special cycles to route accesses through PCI bridges.
So, Mediator is one segment, but all the hardware on the Crescendo on another one, including the PPC CPU.
So, you may plug it in, but you cannot access it.
Michael