You could also always bore out your tripple trees to accept the 250r forks. I believe if you swap the trees, you loose some rake, because the 200x tripples have the rake built in. Also, the 200x headlight bracket will not bolt right up, and the front brake line will be too short, so you may need the 250 line. I was looking at my 84 R forks side by side to the 200x the other day, they are at least 3 inches longer. I beleive you would have to run the R front rim and brake as well. I know the front axle is shorter on the R. Just some things to keep in consideration.
THE 80's RAGE! Currently owns:
81, 85 Yamaha Tri Moto 125
83 Yamaha Tri Moto 200 x2
82,83 Yamaha Tri Moto 175 project
85 Yamaha Tri Z 250
84 Kawasaki Tecate 250
84 Honda ATC 70
85 Honda ATC 350X
84 Honda ATC 250R
(2) 84 Honda ATC 200x
82, 83 Honda ATC 185s
81 ATC 200
Lots of other parts and bikes