Given the reduced blast effects of conventional bombs in AH, a WWII era A-bomb model could be done so it would have just enough punch to level a strat target, HQ or large airfield if dropped dead center.
Should it be perked? Yes
Should it have kill shooter effects? Yes
Should it only be allowed from a B-29? Yes
Should the B-29 be perked? Yes
If we did get a perked B29 and perked A-bomb, the kill shooter effects alone would deter the bomb being over used in high traffic areas.
I know if I paid 200 perks for a B29 and another 100 or so for the bomb, I certainly wouldn't want a KS death from it, so I would go DEEP into enemy territory to drop that sucker.
Considering the high asset value of the B29, every enemy fighter that knew you were there would be coming after you. This would mean you would want some dedicated escorts to get you to target.
The B29 with A-bomb option could bring a whole new level to organized missions.