Here's a little lens I've only used once, but it was on 10x12, and it covered! A Scientific Lens Company wide angle, labeled 8x10:
New lens... by Scott --, on Flickr
I measure the focal length at 5-1/2". It's got a wheel aperture, from f/16 to f/256 in US stops. Glass is in nice shape; aperture moves with just the right amount of friction. This lens does come with a flange!
I used this once for a goofy portrait of the boy:
Scientific Lens Co. W.A. 8x10 by Scott --, on Flickr
Had planned to use it for some 10x12 work, but alas, t'was not meant to be. The lens lit up the ground glass to the corners on 10x12 at infinity; it should have no problem with 8x10 or smaller.
Offering at $225 plus insured shipping and PayPal fees. Please PM me with any questions. Thanks for looking.