Strange how it didn't occur to me the TA/TNP controllers' cars were wider than the other non rail vehicles (let alone how they fit on what I call the "universal toy gauge"). Given they have unique wheels with (what look to be) larger tyres, did you have to cut Winston's mudguards to allow the new wheels to fit? Please show him from the side so we can see how the conversion turned out.
I knew this would look more proportionate (in scale). Apart from the thin walls, the clearance above a TA/TNP engine seems closer to that of many actual sheds (even in the series). For example, the TV version of Ffarquhar Sheds has that much space above:
However, Railway Series illustrations (although not consistent) look more like the image with the TOMY engine, so the entrance height is not necessarily too low: