I confirm those miles based on a route through eagle river, Conover, land o lakes 3 to watersmeet, 3 to Bruce, 3 to Rockland, grade to Houghton.
I ran that trip last year in just under 6 hours.
I would also consider one of the loops back through Greenland or just make the trip all the way to Copper Harbor (another 55 miles in about 2 hours)