Thanks Thomas / Shawn for the quick replies!
I shot a roll of 120 thru the old Rolleiflex this morning given the above information and guess what, it worked! Well sort of. It is a rainy day here in the pacific northwest but even so I think that 9 minutes was way short. As for ISO, I am thinking that it is gonna be hovering around the 50-64 mark. I will try again tomorrow morning with longer development and see how that works.