RIO 6/7 Midspey
SMS:
I have fished a RIO Midspey 6/7 full floater on the Orvis rod you reference, and found it to be a great match for the rod. As suggested by Ted (t_richerzhagen), if you prefer the rod to load deeper into the butt, which on this rod I don't, RIO Midspey 7/8 is probably a good choice. Good fishing.
Todd