I have a prometheus in my 3000T and i just love the voodoo 3 im using right now, the speed difference when you crank up 1600x1200 resolution in wb compared to an cybervision 64/3D that i used before is just insane (could not even get that hige with the cyber)
So just find yourself som pci extension cables and you should not have to much of a problem to fit everything inside with the top closed.
Put the prometheus on the bottom zorro and you should have the space you need.