The coco3 core seems to be available through some closed member list only. The question why that is and how open the license is.
Then the coco3fpga uses sram which would have to be mapped to the mists sdram. This is possible but would probably limit the "turbo" capabilities.
But the biggest questionmark is with the software download. It seems the normal way is to use a pc tool named drivewire with the pc connected to the fpga board via rs232. This would likely need a majpr change to become more user friendly e.g. by using the mists osd for program upload from sd card.