According to Karl Friday (menkyo kaiden in Kashima Shinryu), there's no evidence supporting Ueshiba's ever studying KSR. There are some folks who have done so in the Ueshiba lineage however, and there's some debate about whether or not they're actually qualified to be teaching KSR, but that's a whole 'nother cuppa fish.
Look here for more info:
http://listserv.uoguelph.ca/cgi-bin/...aido-l&P=R4657
or here:
http://listserv.uoguelph.ca/cgi-bin/...aido-l&P=R8456
I've heard of some connection between the Ueshibas and the Kashima Shinto Ryu, however, but have no firm info on that.
Chuck