I've discussed this before. My reasoning was along the lines of the US M-23. That tank used mostly Sherman parts but was much lower with better armor arrangement.

The idea with the Pz IV I have previously suggested is that the Germans:

1. Space out the suspension bogies from the hull and add additional leaf springs to allow an all-up weight of about 30 tons.

2. The tracks are widened to lower ground pressure. Since the suspension is spaced grousers are not necessary for this .

3. The hull is redesigned with a sloped front and sides above the tracks. The armor on the front is about 50 to 60 mm thick with an effective thickness with slope of about 100 to 120 mm. The side armor is effectively 35 to 40 mm thick but remains the original basis.

4. A new turret with overhanging rear and sides is installed allowing a 75L55 to L60 gun to be fitted (a cut down version of the Panther gun). The turret itself uses a saukopf mantle and is similar in design to the Henschel Tiger II design minimizing frontal aspect. The overhang design gives sufficent room for the gun to recoil and be loaded.

5. Shorter skirts are introduced to protect the lower hull from Soviet ATR fire.

6. The engine is bored out and stroked to produce about 10% more horsepower keeping the speed the same for the additional weight. A new transmission with 1 additional gear is introduced and all gears are re-ratioed to give better performance with the new design.