I expect that Bob is trying to replicate the 3-view of the original. As such, of course the dimensions are way off base by modern thinking. At the time, line tension was the big bugaboo. Palmer's differential flaps, the extreme engine offsets and rudder deflections were symptoms of this miasma. We have since learned that minimum drag to maintain speed, coupled with the correct lift on each wing yields a plane that will turn without staggering in one mode or another.
All that in consideration, if you want an authentic OT model, you buy into with all the wrinkles, warts and crotchiness of the original, or go fly something else. For example, scale down an Impact, Vector, or other modern ship and be done with it. Anyone can "improve" the old designs, but what is the point?
That is what OT and Leprechuan are all about, nostalgia!