After looking at everything I can find, the only thing that seems to be generally agreed on is the the hull dimensions are pretty much identical for the E-50/75 & the Tiger II, so at about 7.4m 131/2mm seems good for 1/56. (as I stated earlier, the glacis is different, at a more pronounced slope of 30 degrees.) The 'technical drawings' in common circulation are pretty inconsistant as it looks a bit like they pulled their scaling bars out of the air as they'd produce a vehicle length of about 6.75m - certainly too small.
(There's also still the reasonable point that, despite Jentz & Doyle pointing out that the original plan was to move to a rear drive system, the diagrams they supply for the hull aren't long enough to contain it, so we're left with a somewhat magical interpretation - but hey, this is a vehicle where the 'real' blueprints are nowhere to be found so supposition is the name of the game. The only E series we can have any certainty about is the E-100, since a hull was built & a good number of photos exist for reference - I think my favorite being the one with a Valentine Mk11 parked next to it looking like, given a ramp, it could just as easily have parked inside it.)
If it were me making this, I think I'd be inclined to ask Ken Overby (of Cpl Overby fame) what numbers he used in creating his lovely 1/72 versions, as getting 'historically accurate' ones is like trying to nail jelly to a wall, so within those constraints simply going for something which looks right & doesn't immediately spit in the eye of rational engineering seems the way to go (oh, & if it looks cool too thats a bonus).
Pull the trigger on this one please - I'm unreasonably excited at the prospect of pushing this around the table & beginning to make involuntary tanky noises
