I would highly reccomend a revalve and proper spring. I just did it to my bike, front and rear, and the bike is soooo much more fun to ride. I believe the rear spring valving is quite soft in both comp, and rebound. Forks are a must, at least heavier springs (unless youre really light). I do always revalve and spring my race bikes, and it's the most bang for your buck you can get. I believe there is a forum sponsor that's reputable (in AZ?) and I will reccomend talking with Nick at Pro-Valve MX in CA for susp. needs.
GL