For a plano-convex lens my experiments showed coverage of an image circle of 1/2 the focal length. YMMV, depending on the f-stop you want to use and how much peripheral blur you want. A PCX lens is pretty poor performance with a flat film plane.
You may want to try a meniscus, convex side to the film and the stop in front of the lens - called a "Wollaston Landscape Lens". With a suitably small stop you can get coverage about equal to the focal length.
For a lens you might try a 49/52/55mm +2 close-up lens - it's a 500mm meniscus. You can also try two +1 lenses around a central stop - this will correct the barrel (stop in front) or pincushion (stop in back) distortion you get with a meniscus.
f14 is about the optimum stop, however if you want an image circle of ~500mm you won't be able to put the stop at the optimum location with only a 50mm diameter. The location of the stop is about 15% of the focal length distant from the concave side of the lens. With a 55mm close-up lens and the stop 75mm in front of the lens the coverage circle before vignetting would be 14", not really enough for 11x14. However, you should have coverage if you move the stop to about 50mm in front of the lens.