I'm 240, and doing ok with the stocks so far, set on max preload, with about 5000 miles on them. They actually seem a bit harsh, but that doesn't bother me, no farther than I ride. Longer shocks and I couldn't get my leg over the seat.
Be very careful with cheap shocks. A few years ago, I was given a dilapidated old Goldwing. I decided to fix it up. On the cheap. The rear air shocks no longer held air, and were too rusty to repair. Decent Progressive air shocks cost over $300, so I bought a pair of cheap non air shocks for $100 off eBay. Uninstalled they were the same length as the stock ones. But after getting them installed, I noticed the bike sat too upright on the sidestand. The first speedbump I hit bottomed the rear fender against the tire. Basically $100+ shipping+ labor wasted.