I am plenty good with the MK6 but it's turret gets creamed by arty and premium ammo and the hull is only good at hull down even then it gets penned.
"It would be nice if it had the hull armour in real life"
"The hull is only good at hull down"
That second statement is more or less British tank design philosophy of the entire Cold War.
Even if it did have a 120mm LFP, it'd still be easily penetrated by other guns at tier.