To me, that would be simpler....B would take results of play, thus series over. With A recovering the ball, Mike is correct in that (same as HS) A would get a new series; A can have multiple series in OT anyway on Saturday (i.e. just gain 10 yds). As far as carrying over penalty to B series, the laundry list of fouls in rule 3-1-3 does not include KCI fouls, unfortunately.
Having said all that, I'd like to think this question illustrates a hole in the rules....to me, a previous spot enforcement WOULD be the most logical, but the rulebook in it's current version does not support that; unless, I've missed something...which is not out of the realm of possibility.
Personally, I'd like to see an AR on this to help me sleep at night.