Joe: The ASA standard thickness for 11x14 glass plates is .080 t0 .095 inches. Kodak states in their old publication no. F-5, Kodal Professional Black-and-White Films, sheet film is up to .009 inches thick. I've used much thinner litho film and slightly thicker GAF film. These figures agree fairly well with your measurments. I don't trust paper to remain flat in a film or plate holder. Humidity might cause it to bulge away from the septum or glass backing. A few pieces of double-faced sticky tape might eliminate the potential for this problem.
I don't have the ASA specifications handy for 11x14 film or plate holders, but the distance between holder face and septum face for an 8x10 film holder is .260, + or - .016. The slot for the film is .012. The thickness of the film holder is .594. I would assume that the holder face to emulsion distance is the same for both film and plate holders. These tolerances might seem awfully sloppy to a machinist, but at the apertures commonly used in LF photography, they should have little effect on practical photography.