Pretty sure the Rox bolts for the size I used on my YZ250 were M8x30. That might add 5mm to the length that came with them just to get 100 percent engagement of the aluminum threads. I wouldn't bet money I didn't get 35 without going out to the garage, though. It's been a couple years.
The only stainless bolts I like for a structural application are from ARP in California. Expensive, but seriously strong, with integrated flanges in their heads. I replaced a lot of stuff on my Husky with them when it became clear that the OE fasteners were made of high-density Play-Do.
DIRT BIKES ARE FUN AND INTERESTING