There are Winston owners on this forum, but most seem to use 4 and 5 wt rods, and a couple have the BIIIX in 6wt. Winston makes the faster SX series, and that might be better suited to the conditions shown in your fantastic pictures. The folks at the Winston forum would be able to help you decide which Winston
rod is best suited for your father, but they will not recommend a Sage....ever. I like Sage, and the Sage ONE is reported to perform very well in the heavier weights you're looking at.
Of course it will ultimately be your father who decides which rod suits him best, so get one with a return policy, etc.