Kinda reminds me of the tier 8 american medium tank, the T69 from World of Tanks. In my own personal opinion, the 76 mm gun was better than the 90 mm gun for multiple reasons...

76 MM GUN ADVANTAGES:
-Uses APCR ammunition which RARELY bounced
-Slightly more accurate as well was good aim time
-Quicker reload time (Like 16 seconds with the right crew and equipment)
-Slightly quicker rate of fire (Firing a round every 1.5 seconds)
-Weighed less and increased acceleration and maneuverability slightly

90 MM GUN DISADVANTAGES:
-Slow reload time (About 30 seconds, and would worsen if the ammo rack got hit)
-Slightly decreased tank's maneuverability due to weighing more
-Used standard/regular AP rounds which bounced damn near 65% of the time
-Accuracy was slightly off (It would be 50 times worse if the gun got damaged)

But again, this is just an opinion. Nice pic still.

Except now the T69 sucks due to a armor creep and less and less tanks able to be penned easily by it, I remember back when i could hold my own reletively easily, now its harder.

Actually, accord to rumor, it got a slight armor buff. So even if the gun and maneuverability got slightly nerfed, you'll still be able to bounce some stuff off. Then again, I could be wrong.