Thanks for the responses.
I looked up the prototype LMS Stanier Coach and they were 65 feet long, not 75 or 85 feet that I thought they were prior matching the length of American rolling stock. That 65 feet would translate to 10.3 inches in OO Scale and 9.0 inches in HO scale. That's okay with me and my visitors will never know/care about that small difference (to them all passenger cars look the same unless double decked), just like they do now when they see 1:43 vehicles next to 1:48 scale train cars or my OO British Leyland National 40-foot bus next to my HO 40-foot Fishbowl buses.
For the record, Lionel's "non-scale" Stanier coaches are 15 inches long or 1:52 scale.
