This is excellent advice. The very wide rims you are considering and consequent tires will absolutely KILL the handling of this bike (I have a 400F for reference). A 90/90 and 110/80 combination will work very well depending on the tire brand. A 120/80 will be ok on the back if you want a beefier looking tire, but it's a big tire for your bike and the 110 is better in my opinion. My 400 is a disaster with even a slightly too large front tire, and your 350 likely will be similar. I have a 90/90 tire on a 1.85 x 18 rim on the front of mine, very noticeably better than the 100/90 previous tire which made turn in awful. I would not fit larger than a 1.85 front rim. Of course, you can certainly fit much larger than stock rims and tires and your bike will still be safe to drive, but you will have no chance at all of keeping up with a stock bike in the turns, so if you truly are more interested in building a good handling bike, don't go beyond one size up on the rim width and keep the tires light. Also, if your 350 is as physically similar to the 400 as it appears, a 3.00 rear rim and tire will very likely interfere with the chain. I have also bought many rims from Mike's XS and have been very happy with them, though a couple needed some file work to level out the bead seat across the weld. The stainless spokes are also fine, though it can be tricky to figure out the right length as they sell model specific spoke sets and if your bike is not listed, you are on your own for fitment.