Hmm. The word coverage has been used three times so far in this discussion, never pointedly enough.

Clem, most , modern w/a lenses (from, in alphabetical order, Fuji, Nikon, Schneider and Rodenstock) all have ample coverage for their intended formats. Some relatively modern w/a lenses, e.g., 65 mm Super Angulons, just cover 4x5. Not all older w/a lenses for 4x5 have coverage to spare; in particular 90 mm Angulons and Wollensak Raptars, also sold by Graflex as Optars.

Go here to see Schneider's coverage claims. Go here for a larger but somewhat incomplete and out-of-date list. 4x5 needs lenses that cover at least 150 mm.

About distortion. As has been pointed out, w/a lenses for large format cameras have low distortion. The standard w/a lens effect -- objects near the lens are much larger on the negative than distant objects; think big nose, small ears -- is sometimes called distortion. T'ain't so, failure to render straight lines as straight lines is distortion.