Actually, I was referring to the swingarm itself - independent from the frame. Sounds like you have things pretty well thought through. Seems like I often see people underestimate both the importance of stabilizing a two shock arm, and severely failing to grasp the enormous changes to the entire chassis with any version of a single shock. Thought your lovely swingarm might benefit from a larger diameter axle as the physical size, or even spacers and associated component diameters is where all the stiffness value comes from (with regards to the axle). Had the notion that since you upsized the front bearings to accommodate the larger Suzuki axle you might reap the same benefit at the back. I realize keeping the Suzuki axle worked out to a straight forward way to mate up the parts, but Suzuki made that axle a lot larger for a really good reason!
No doubt getting the overall frame stiffness up to par with the new suspension will be the big challenge, but every bit helps! Keep up the great work!