The 88 with shield, which are supposed to be mainly used as AT gun have only 6 time fuse shells I think. The ones without shield should have around 50 shells though, as they are usually supposed to be AA and AT gun at the same time.
Giving the AT ones more time fuse shells would be a minor buff, but as enemy airplanes' average altitude is right where you can't see anything becauseof the shield, it will probably not do much.
I suggest to replace that AT-88 on Cobra main base and the one at the airfield as well with one without shield and those 50 time fuse shells, as you usually don't see any tanks with them anyway, and with the removal of the shield you still can shoot tanks as well. Furthermore real AA- 88's close to airfields make sense anyway and might help balancing the issues of Cobra.