bigger guy, with 120hp on a +12 arm IMO a 14 stag extreme is to much tire unless in a real short roll out. Another part to the puzzle, is this a stock chassis?
Here are my two suggestions: assuming the arm stays +12
1. stock frame - +4 in front : 12 pdl 72 RO stag extremes/14 pdl 72 RO non stag ext , 16/44(if under 235lbs)16/46 (if over 240 lbs)gearing, leaving in second, shock setup stiff but to slightly say on launch with the swingarm level to ground.
2. +6-+10 out front: 76RO 14 pdl non stag ext/72-74RO 14 pdl stag extremes, same gearing and shock stiffness but swinger pointed slightly up hill(very minimal).
Chris
Wheelman