If you are going to be running 25's in the rear, I would recommend keeping the front a 25 also, to keep things blanaced. You dont want your 3 wheeler to ride like a low in the front, jacked in the back dragster. I would deffinatly go with a general square nobbie for the front for best handling on that machine.
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