illumiwhatsit, David, are you sure that a 168/6.8 Dagor will cover 8x10? Cover as in put good image in the corners, not cover as in put light in the corners.
For something critical, like a commercial architectural image that's going to be enlarged for a glossy poster, it might be marginal in the corners, and I don't see myself using an ancient uncoated lens for that anyway, but stopped down, the older 168/6.8 ser. iii, or at least the one that I have, is good enough with a few mm to spare for the 8x10's that I'm likely to make with it--namely landscapes and architecturals that I'm planning to contact print. Since it's such a compact lens, I also like it for 4x5" when I need lots of image circle.
According to Goerz's own catalogue, at f:32 a 6" Dagor should cover whole plate, and a 7" should cover 8x10", and 168mm would be somewhere in between.
Sometimes, all one needs is to put light in the corners, as long as there isn't any important detail there, and as long as the image isn't terribly distorted, like, say, at the edge of the image circle with an Angulon where the image quality drops off quite radically.