Hi Gary, I found my Nikkor book, and the 450 M is spec'd to 440mm @f/22.
Fuji specs the 450 CMW to 520mm@f/22.
The Nikkor's coverage is limited a LITTLE by the shutter, it would cover a couple more degrees if the diameter of the shutter were greater. The Fuji is limited a LOT by the shutter, it could cover ten degrees more in a larger shutter. Neither come close to the 12x20 format !
Just what ULF shooters are willing to accept in the corners is outside of my expertise. In the old days, I shot 8x10 chromes and clients used loupes in the corners, and the specs from the maker was a serious number. Contact prints, well, you're on your own. But if the Nikkor will do it for you, the Fuji will do it better.
I have to yield to the ULF specialists. Good luck !