William,
I think a pair of H-48's @ 63 mm would be the way to go, not 1667's @ 66 mm?
I think that is way too much diameter for twin 67's, or 80's. The H-48 is really just
a cut down 1667. And 6.50" cup is also way too much cup for that set up. I would
start with 5.63" and once you run the boat more try 6.00" cup.
Just a few suggestions,
Mark