What you don't know is that the maus actually began production but there was only one turret and two hulls finished before the russians took the factory, and the complete one went through testing like a beast, and at the time there were almost no tanks on the allied side that could pen the maus, and the fact that they were set to operate in pairs meant that you would almoat always loose, the maus is actually one of the most advanced tanks designed in the second world war, I think the complete one is on display in a russian museum, or maybe moving to, it would possibly have won the war if it had been deployed, and the turret was NOT hand cranked, it was far too hard to hand crank a multi-ton turret. Most of the things you put up for changes could be overlooked, I think if you just updated armor and armament, it would make a far better tank today, the only reason it was so slow is that it had electrically driven drive wheels, and the engine was a simple generator, also the mantlet was SEPERATE from the actual turret armor, and this means it was thick af spaced armor and spaced armor has a habit of eating HEAT, now modern heat would still kill it, but none of these tanks would be completely destroyed by one shot unless it caused an explosion as there were armor plates and a motor between the drivers and the main compartment, so it would take at least 2 barring a magazine shot or similarly lucky hit