A little thing from wiki about it's gun:
"The main gun was a 7.5 cm Rheinmetall-Borsig KwK 42 (L/70) with 79 rounds (82 on Ausf. G) with semi-automatic shell ejection. The main gun used three different types of ammunition, APCBC-HE (Pzgr. 39/42), HE (Sprgr. 42) and APCR (Pzgr. 40/42), the last of which was usually in short supply. While it was of only average caliber for its time, the Panther's gun was one of the most powerful tank guns of WWII, due to the large propellant charge and the long barrel, which gave it a very high muzzle velocity and excellent armor-piercing qualities. The flat trajectory also made hitting targets much easier, since accuracy was less sensitive to range. The Panther's 75 mm gun had more penetrating power than the main gun of the Tiger I heavy tank, the 8.8 cm KwK 36 L/56,[52] although the larger 88 mm projectile might inflict more damage if it did penetrate.[53]"
If anything, it would probably be perked at what the Tiger sits at now, and the Tiger's perk price would drop by 5-10. I wouldn't drop it any lower than 10, since it DOES have a good amount of armor. With excellent armor and a deadlier gun than our Tiger, it's going to definitely be perked. I foresee the demise of many a T-34 by the oh so beautiful Panther.