I always thought a better approach for the 2000 would be to design something that attached to the accellerator card. Nobody's running a stock 2000 anymore. I know the specs of the Commodore 030 slot are available... not sure about GVP. Perhaps something that fit under the cpu chip itself...
just a notion... but it would get rid of the Zorro II speed and address space limits. I did some searching a while back and found it's possible to do a 68000 to PCI interface with 2 chips.