Don't do it

I can attest that both John Deere and Kawasaki snowmobiles are good, reliable machines.  After a couple of restoration projects I will say that the John Deeres seem to be a simpler design with fewer parts.  The TPR sides of the belly pan are kinda flexible and flimsy (hard to find a NOS set too, good used and repops are out there) but DAMN! the center belly pan is tough as heck..

Be sure to look for the ones with the full rubber yokahama track vs the grouser bars, the seat bottom and cover are easy to find and replicate. Decals are colorful but a bit expensive ($150-200 for a set.  Go for the high windshield but be careful to adjust the handlebars as the will likely contact make in a full turn.  The 1980 340 trailfire was my entry the JD herd  it is light, spirited but doesn't turn as well at slow speeds as I'd like (not much weight on the front skis)

Get one, you'll appreciate and enjoy the differences!   I did pick up a 1981 440 Trailfire. I like how the engine cover hinges up to give you easy access to the carb. I haven't gotten to ride it yet though still waiting on some snow. Thanks for the input!