The Woolwiches were a good six inches wider than the N they originated from. Also the K1a/393 were given 6' drivers.
The SR U had a different wheelbase and boiler pitch to the N/Woolwiches, and were subdivided into low or high footplate depending on whether rebuilt from the K tanks (longer frames behind the rear axle) or built new as Moguls.
The N1s are probably the easiest variant of the N, but again there are differences in front footplate, cab front, and no. 822 in particular had a somewhat different valve gear arrangement.
Maunsell Moguls are not easy to model, even though they look superficially similar. Kit manufacturers do get it wrong, especially when trying to portray the U.