The 350's rear fender, subframe, and taillight weigh 3lb 7oz.
The 250's fender, subframe, light and license bracket weight 7lb 8oz. The vast majority of the weight difference is in the license bracket. I'll be attaching the license directly to the fender and saving all that extra weight.
Because of all the offset locations of linkage parts it's tough to determine if all the rear end linkage geometry is identical between the two bikes. Everything looks identical, except the 350's swingarm is 3/16" longer.