I fully agree. Nixon vs. GSA doesn't really serve as a rallying cry to presidents wanting to withhold information. It is merely useful in determining (for the first time that I know of) that former presidents do have a legal right to retain their files after leaving the office (apparently for 12 years).
As far as the other links, 44 U.S. Code Chapter 22 is a law I didn't know. I thought that the law for presidential ownership of records only existed as stare decisis. I didn't realize it was codified anywhere. That is fantastic to know.
The executive order, I have read before, but had forgotten about it. It does answer my original question very well...the procedure around claiming a pres priv. Of course, you never know with these orders. They could be gone in 2 weeks for all we know.
Thank you obi! As I said, this is an area of law I don't know very well...and you are the only one to provide any useful information on the topic.