Not a completely bad choice. However, be sure you understand that the AP ability of the 76mm main gun is LESS than the US M4 Sherman's 75mm main gun. It is the same gun as the T34/76, which means is it the bottom of the barrel in terms of tank AP performance in AH. With that in mind, the HVAP will make up for that at distances INSIDE 1200 yards or so, once outside of that the AP ability of reduced in a major way. The rate of fire probably is faster that the T34/76, but still.
If HTC is going to add a SPG, or an "assault gun", then perhaps may I suggest the German StuG III (or StuG IV) or the Soviet Su-100. The StuG IV chassis is already in game and the Su-100 chassis is already in game. The StuG III would have to be built from the ground up.
