[JERSEYDEVIL]

my thoughts
either you might want to consider a different buggy for your build or a different engine to swap into your buggy.

1) i'm not so sure how a polaris engine/tranny combo would fair mounted to a swingarm, bouncing up and down.
2) the wait of this combo might be very taxing on your axle/ hubs
3) a swingarm setup is only comfortable up to a certain speed on most trails. i cant tell you how many times i had plenty of pedal left on my yerf and couldnt use it because of the rough terrain and i have a ton of time ,fab and $ in handling mods. including extending the swingarm 3" which helped alot
4) to get the maximum impact from a 500 swap i would definitely fins a 250 I.R.S. chassis