Buy a little storage compartment from Menards and keep both!
They are both cool sleds. I have owned my '75 SnoJet Astro SS since 1979. It has a mild, 32 HP, fan cooled 340 Yamaha motor.
The 340 F/A would be an SST model, but there is virtually no difference between it and my Astro, other that the much hotter engine, and a different (Arctic Hex) clutch.
My SnoJet is extremely lightweight, extremely easy to work on, has been very reliable, and absolutely great in deep snow, due to the tapered tunnel. Parts are still fairly easy to find.
I would look closely at the track. These had a spring steel bar style track....much like the 1st Kawaskis had, which required a recall to replace the steel bar tracks.
Those steel bars can come loose or break, and good, original tracks are getting hard to find.
You can convert to a different track with a little bit of work....either a typical 121" track, (which requires moving the suspension backwards, and probably having to remove the snow flap) or, better yet, a 116" track from a mid-eighties Yamaha Phazer, etc....or something similar.
The Sno Jet guys love those F/A SST's....you certainly aren't going to lose money at 400 bucks, if it's nice and runs.
I don't know much about the Deere....but there are still a bunch of Deere sled enthusiasts around that would want it.