The 155mm is not a stretch, the US used a 203mm and 240mm M1 artillery piece during WW2. Personally, I think its overkill, as you could shell a target from well outside dar range. Imagine chucking a 165lb shell 25,000 yards...I think a 105mm is more than sufficient for gameplay, either as a towed unit, or in a SPG chassis.
Regardless, the concept of towed artillery in the game adds a hole new element. Yes, they're lethal at leveling a town or base, but they're equally vulnerable to air or GV attacks unless protected by AA units and tanks. Targeting and ranging would have to be improved, as simply lobbing shells onto a town without the ability to direct fire is pretty much a waste of time considering the ammo that could be carried.
Directed artillery fire during WW2 could be very precise, so perhaps having a Jeep based spotter with some sort of targeting ability could be an option...make effective artillery a team task, and you've got something.
Personally, I'd like to see those useless 37mm AA guns replaced with the standard 40mm Bofors gun. The rate of fire is identical to the naval AA guns, but the ballistics and accuracy are considerably better. I only go to field AA when the hangars are down. I'll take my chances against fighters in an IL-2 before I go to the 37mm.
