Whats the reason you want to go to an extended swingarm?
Personally on a Warrior/Raptor 350 I think an extended swingarm will actually have too many negatives to be worth while to run... They decrease traction, turning radius, and balance.
The only real advantage on them is drag racing, and for hill climbs / high power dune machines where you want the weight to be placed forward more to avoid having the front come up.
On a trail, woods, or mx bike the longer swingarm will make it much more difficult to maneuver, and also the bike will not fly well should you jump it.
Also if you extend the swingarm be prepared to buy a new shock because the stock one will not be able to perform at all unless its a small child riding the bike due to the added leverage.