My 8 3/4" Verito covers 8x10. I had a 9" at one time, but never tried it on 8x10. I don't see why it wouldn't cover if the slightly shorter lens does. Does the OP have a 9" Verito or is he only considering buying one? 9" is kind of short for doing portraits on 8x10 (if portraiture is even the goal).
But that brings up another factor. If the lens is to be used as a portrait lens, then it will probably be used at extensions greater than the nominal focal length, which would allow for somewhat better coverage.
Speaking of coverage with regard to a Verito is a little misleading. Coverage is usually taken to refer to an area of critical sharpness inside the circle of illumination. And a Verito is not critically sharp anywhere. My experience with Veritos is that they do have a wide field of illumination, although the image tends to suffer the further off axis one goes. But again, subject matter and the way the lens is used has much to do with its suitability. If your subject matter is close to the center and the edges of the field are out of focus and darker anyway, then what the lens is doing out there isn't really noticeable anyway.
I'd like to ask the OP what he intends to photograph and what he's trying to accomplish before determining if a 9" Verito is suitable or not.
Removing the front cell will yield a lens with a longer focal length and a slightly slower speed, but with similar characteristics otherwise. I didn't find a conversion focal length listed for the 9" lens, but an 8 3/4" Verito converts to a 14" lens with the front cell removed. The 9" should be similar.