Should I trade this for a '95 Air-King?

[77T]

The appraisal is usually set for insurance coverage replacement value. Trade-in's require discounting so the shop can make a profit.
So, even if they could get $3500 for yours, the trade value would be 2000-2300.
There is very low demand for your watch in US because few collectors seek it. The Lemania chronograph movement is in several brands, but their own watches seldom with are seen. I've not seen any for sale here in past few years. On Chrono24 similar ones go for much less than that appraisal.
All in, you'll prolly get an offer of 1000-1200 and you will be asked to add 1000-1200 cash to get the Air-King.