This is some great info. I would love to see the new seats as I have been eyeing the Status SPAs. Plain and simple don't fit in my stock seats it seems at times. I am not sure if they are universal with the 70/37, but I had seen these seat rails on G35 forums. I know you are looking for mounting brackets, but maybe could use these too.
FS: G35/350z Buddy Club Super Low Seat Rails - G35Driver