I'd love to do this mod too. I would guess you would need handle bar risers with that seat. Both those mods would vastly improve our snowmobiles urgonomics.
I have a 5 inch with pivot and it is very comfortable with the Boss seat. I had to extend the brake and throttle and got rid of the parking brake. I am 6 ft and my son is 6-2 and it is much better than stock
I ordered a 3" pivot riser so I don't need to extend the cables. I will be switching back and forth between my Boss seat and OEM when I have a passenger.