Sumtoy .660 or .650, also 5's or 6's?
Personally I would go with the .650 #6. Give William a ring and he will hook you up. The good news is that he stands behind his product and if the choke you get doesnt produce desired results he'll swap it out for you. Cant go wrong with Sumtoy imo.
I choose 6s in either and lean toward the 660. Wm will know which based on your desire. I know that the 665 range for Remington is still good for 6s. I believe that the Rem SF hevi-shot rated 12 ga is 675 and it patterns the old Rem HS #6s very well.