PzC:
Init |HA | GD | CD
IS-2 12 | 18 | 26 | 6
Panther G 12 | 17 | 19 | 4
King Tiger 14 | 24 | 26 | 6
Pz IVH 9 | 13 | 14 | 3
T-34/85 11 | 17 | 14 | 2
PG:
IS-2 8 | 21 | 18 | 2
Panther G 12 | 21 | 18 | 5
King Tiger 14 | 25 | 21 | 5
Pz IVH 10 | 14 | 10 | 2
T-34/85 6 | 13 | 15 | 2
The main point why IS2 was much "weaker" in original PG was the much lower initiative and the very low close def value. In PzC the IS-2 is a tad stronger than Panther which is OK due to its equal initiative value.
In PG the IS2 always had to take the first fire because of the very low Initiative and the remaining units just did not have enough power to really damage a lot of german tanks.
The T34/85 is even stronger changed between PG and PzC...in PG again due to its very low initiative the T34s had to take the damage first and the backfire then did not make soo much damage to the german tanks.
In PzC this is reversed the Pz IV has a comparable low initiative (unrealistically low ?), while the Def values of T34 and Pz IVH were comparable which is well reflected (in PG the Pz IV even had much weaked GD !). The 85mm gun of the T34 is also stronger than the 75L48 of the IVH, but I think HA13 is too low for the IVHs - but again the major weakness is the now lower initiative value for IVH when comparing to T34.
Btw. Infantry Close Defense =2.
So even for infantry it will be nearly suicide to attack a close defending IS-2 or King Tiger.
Also strange, why is the Panther G having lower HA then Panther A and D ?!? (HA 19)....they sure used the same gun and the same ammo all the time.
HA of IS-2 is fitting, slightly better than the 75L70 of the Panthers but lower than the 88L71 from the Kings, GD is around equal between IS-2 and King. So thats OK for me.
T34 and Pz IV comparison is also fitting better than it was in PG, only maybe inititiave for IVH could need a buff so it is not cannonfodder for the russian standard tanks. Should be more of a 1:1 situation IMO.
Now for bagration the major problem is just the extreme unbalancing of the russian army composition.....the only issue is the absurd number of IS-2 in the bagration scenario which makes it so impossible to win, considering the much weaker axis forces when comparing to the original PG bagration scenario.
In reality the IS-2 were produced in fairly small numbers...compared to the T34/85 (only THIS model) the numbers were IS-2 to T34/85 were 1:10 !
In the scenario this is waaaaaaaay off. In combination with the comparable ultra weak composed german army the axis stand nearly no chance - though of course a very skilled player can make the difference as always, or kerensky just had luck

. But I will try the Jagdpanther approach since with a cost of only 465 and the following stats:
Init |HA | GD | CD
Jagdpanther 14 | 24 | 19 | 1
It is good enough to kill of T34s due to the high initiative and has good chance to kill suppressed IS-2 or survive IS-2 attacks - DESPITE the AT malus on inititive.