100 landed at Normandy is irrelevant to the discussion as about half of Shermans produced in late '44 and '45 were equipped with 76mm guns.
I have no idea where you get the idea AP was scarce for this gun. It wasn't. HVAP was scarce, but that is true of all specialty ammunition.
Not sure how you can say it wouldn't be competitive when it has already been stated that it would be nearly equal to the T-34/85 and is in every way equal if not superior to the PzkwIV we have in game, both of which are used in abundance in the LWAs.
Here's some info on the ammo needed to compete with the the panther and Tiger. Regular AP was inept against these types. Also The T-34/85 did have better armor then the M4 Sherman. I don't have my penetration charts in front of me but standoff penetration between the two guns I would say the T-34/85 has an edge .
Because of tungsten shortages, HVAP rounds were always in short supply. Distribution was prioritized to U.S. tank destroyer units; most Shermans carried only a few rounds and some units never received any.
100 76mm equipped Shermans does matter to me since it was introduced with only 10 months of the war remaining. By then the Panther already had 2 model upgrades .
Now maybe in the game it will have all tungsten ammo . Then it would be competitive., but as stated if you want to add another tank then at least add one that will at least span a couple of arenas . The 76mm armed Sherman would only be available in the LW arena and IMO would not really do much to enhance that arena.