I have a close friend who flew the Air Tractor 802 as a fire bomber. He liked the Garrett powered airplanes the best because the power response was instant. A PT-6 takes a little longer to spool up from low power. We do need a model of the Air Tractor.
Pawel, I don't think there was any development connection between the Air Tractor and the Dromader, just similar responses to the design challenge, I think. There are some Dromaders in California, I used to see one at Hanford in the central valley.
I do have in mind modifying the Revell Stearman into a crop duster. I used to work on N3N crop dusters but my Karaya 1/72 kit will be stock.
So far as I know, the first conversion of a crop duster to a fire retardant aircraft was an N3N, done at Willows, California. The N is a bit bigger than the Stearman and handled the R-1340 better.