I wouldn't worry too much about the position of it. I have stored them flat, upside down and on end. Never had any issues related to how it was done.
A solid flight case is what I use for my more precious finds. I just found an original Emax rack that has never been used! Can you believe that?
It is in it's original factory box with library and the rack ears are still factory wrapped up in a plastic bag. The guy simply never used it after purchase. I reckon there aren't many of those left around.
Jay
sick !