Yeah the AP rounds would be awsome. And as long as they were limited I dont see them as being unbalancing. 6 or 7 rounds would enhance the game not unbalance it.
The thing is the B-25H is an effective plane when used in missions or with support of some kind, even if just support from other 25H's. To many guys take them up alone, fight them alone, get shot down alone, and then never fly them again. But you get a few fighters to support them and Ive seen 1/2 dozen take a town down in no time and then supress Gvs inbound.