Then simply revert or partially revert the Heavy tank changes its the "safest" change...
I personally think that even if the current situation isn't ideal, it's better than the heavy tank stalling meta that we've had over the last year. Particularly because heavy tank stalling allowed players who were (way) behind to have comebacks with techless call-ins, while the current heavy tank rush meta at least requires a good early and mid game performance to pull off. In addition to that I also believe (and hope) that some additional small adjustments to timing and performance will swing the current heavy tank meta in more of a healthier spot, without needing to radically change or revert anything.
According to Sander93's calculations:
I did forget to include Concentrated Fire in that comparison, which shaves off one shot for the Command Panther. That'd put it around 47s TTK which is roughly on par with the Tiger I.