Panther needs a cost decrease. Stat wise - its fine. If it costed 140 fuel it would be fine, maybe even decrease teching cost of T4 if T3 is not built. (making a T1 T2 T4 more viable)
It does need a cost decrease, but 140 wouldn't make it 'fine', it would make it 'insanely on the level of overpowered cheap'.
For comparison, Sherman costs 135 fuel and T34/85 costs 130(if double) and 140 if single call-in.
Do I even need to say anything more?
Unless you were planning to give a significant cut to panthers stats as well with that ridiculous price you've suggested to actually match it with other similar costly armor.