I see what you're saying GRUNHERZ.
Basing the appropriatness of the tank on the gun makes more sense, barring massive armor upgrades. I'd think the following would make a good German tankset:
Panzer III J (50mm KwK 38 L/42)
Panzer IV D (75mm KwK 37 L/24)
Panzer IV F2 (75mm KwK 40 L/43)
Panzer IV H (75mm KwK 40 L/48) We have this one
Panther V G (75mm KwK 42 L/70)
Tiger I (88mm KwK 36 L/56) We have this one
Tiger II (88mm KwK 43 L/71)
A Russian tank set using the gun as the guideline:
T-26S (45mm Model 1938 L/46)
T-34/76A (76.2mm L-11 1939 L/30.3)
T-34/76D (76.2mm F-34 1942 L/41.2) We're getting this one
T-34/85 (85mm ZIS S-53 1944 L/51.5)
KV-85 (85mm ZIS S-53 1944 L/51.5)
IS-2 (122mm M1943 D-25 T L/43)
These tanks sets would track the steady increase in firepower as the war progressed.
The Panzer III J, Panzer IV D, T-26S and T-34/76A would be used for 1941.
The Panzer IV D, Panzer IV F2, T-34/76A and T-34/76D would be used for 1942 with the Tiger I possible for late '42 .
The Panzer IV F2, Panzer IV H, Tiger I, T-34/76D and KV-85 would be used for 1943.
The Panzer IV H, Panther V G, Tiger I, Tiger II, T-34/76D, T-34/85, KV-85 and IS-2 would be used for 1944 and 1945.