A regular sportsman 500 lift should work on the front. Are you looking to add 27" tires just to the front or the entire machine? With an older 6x6 you are always going to have some push in the handling. Meaning that the rear wheels (since you have four) are always going to push the front of the atv around and it is going to be harder to steer. One thing that may help would be some front heavy duty springs in the front and some good traction tires up front. Just a thought. Maybe some others with some experience may chime in.
Your thought of bigger tires up front may not be a bad idea. Just make sure you do not use Awd while on hard packed surfaces such as asphalt and such.