Tant01,
I am not looking for any names. There are too many people these days running around calling themselves "grandmasters".
As for the bujinkan ranking system it's been a source of controversy for people in and out of the art. I will not comment on the ranking system because I am not qualified to do so , I leave that up to Soke Hatsumi.
There are actually more that 2 Shinan in the U.S. and I have personally trained with 3 of them. If you are in the San Fran area you can visit Dale Seago(
http://www.sfbuyu.com/) who is a very knowledgable and capable 15th dan , if you want to find out more about the art and it's rank structure.