Srx is a great trail sled and some people convert them to mountain sleds, however I think it's easier to use a viper imo. Vipers have more suspension, the deep snow specials (144" track) come with a more narrow ski stance.
I have heard of some people putting a viper skid in their srx and changing the front suspension over to viper also. I believe one of the problems you're going to run into is the front heat exchanger to track clearance.
With a 162 track, you'll have and pay attention to your clutching and gearing also.
For my vipers, I have 4.5" Rox adjustable handlebar risers. About 3" is about as far as you can go without lengthening all the cables.
Not sure if any of this helps but some srx guys will help you out.