Hi Peter,
I'm sure I used to have some info on Oomoto Kyo, you could go visit and train at their Aikido dojo, unfortunately, I don't hvae it any more. I did look up their web site but couldn't find anything mentioning Aikido.
http://www.oomoto.or.jp/
I did however find this, which I think is the same info I used to have
http://www.stanford.edu/~patryan/oomoto.html
It's no longer available, but the Japanese contact may be of some help.
Regards
Bryan