Lets build a tank.

You also need wider bridging for the engineers if you want to cross at least some of the temporary bridges they build. Pontoon bridgeing should be ok though.

 

I'd argue that the 90mm was better and also in production. There was even a turret that should fit although it didn't enter production or did so late (i.e. the M-26 turret). Ammo storage would have been even more of a problem though.

As for diesel not sure the advantages outweigh the disadvantages of having two separate fuel supplies for most armies. Works well if you are the Soviets or the Marines though.

 

Presumably (dangerous word), duckbills fitted within standard bridging widths, since you see them apparently permanently fitted on some Shermans. Maybe just an extension to the same width would fit KB's needs.
If they were adequate enough to support e2 Jumbos I imagine they'd be fine for gun upgrade weight.

Though... The wider the tracks on a given length, the harder the turning, and the more stress put upon the entire drivetrain.

Don't often wonder who made the best tracks...
Soviet ones generally very simple construction, but lordy a T34, no matter what type fitted, makes a very distinctive clattering track sound.
Tiger may win the most stupid track-related issue prize. Two sets? Nein danke.

 

Neutral steer is a nice feature. Did the T23 have this feature?