Going for an American design has the interesting result that it means that the USA is producing a ~400 hp V-engine prior to the M2 medium entering service, which may have the knock-on effect of the M3 Lee and M4 Sherman also going with that engine, thus giving those tanks a lower profile.
But still kept the oversized volume. Hull was large enough to fit the Wright R-1820 with slight modification.
It's totally possible to put a smaller engine in the M4 hull, but Armored Force wanted options to use all engines, large and small, even if was inefficient use of volume. Upthread I posted Israeli Shermans with cut down upper superstructure to lower the tank.
US could have done it, but didn't want to interfere with production, despite having way too many vendors making Shermans.
Honestly, I don't think it was the requirement to fit radials as an engine option that doomed the Sherman to be 'suboptimally' tall, but the lack of a decent transfer box to lower the crankshaft under the turret basket like was later used on the Hellcat. If someone gets that figured out early enough I think we can see the 'sleek Sherman' in TTL. Not sure about the timing though, we're already in early 1939 so there may or may not be time to make major changes to the M3, but I think declaring the M4 'it is what it is' a bit premature.The original models used a radial engine, but if they have a viable alternative before the M3 is even in the design phase... Hells, depending on how much is known about the Valiant while the M2 design is going on we might not even see the OTL M3, as the desners might take some tips from the Valiant, and just install the main gun in the turret, rather than having a it casemated in the hull.
Can't remember if this thing was posted in this thread or another, but a low-profile MG turret on the M3 and a big support gun in the hull is an idea I can get behind.Well, my idea is to have something like the M3, but a MG turret and a 105mm howitzer in the side sponson for an interim support tank