What is funny about that? Jpz4 is designed to ambush and destroy enemy tank, When the pjz4 aim at you, he will be harder to hit than m3 or t70, height is only(!!) 1.85 m, it is wider and longer than m3 and t70, still worth to compensate on that if u can reduce height of a tank that is going to ambush enemy tanks.
Realism vs Balance. A Jackson should be an upgrade for an M10. So I would say 80 Fuel plus 100 Muni would be fair. Since almost all Jacksons were just turrets shipped to Europe and mounted on an M10.
Having Brit Arty emplacements were realistic too. No smoke and the ability to erase squads. US actually were the leaders in Artillery at the time. Realism isnt fun...