Most people that consider themselves III/III+ top out on the Gorge around here, the Lochsa is quite a different river than the Gorge. If you want to check it out I recommend you go with some people you know and trust, and that know that river. The bonus is you can always bail if it's more than you want since it's roadside.
A lot of Class III boaters start the season on the Gorge (if they like cold boating), then head to the Blackfoot when it comes up. The blackfoot is fun at high water, it gets more continuous wave trains than the Gorge's pool drop, but the blackfoots rapids are more mellow, but longer. Then when the Blackfoot dries up, head back to the Gorge. That's what I used to do before I became a Lochsa addict. The gorge is boatable much of the year but a cold snap will freeze it over and it can take a month or two for it to clear. This happened early this December and didn't clear until the end of Janury.
Advanced Hydrologic Prediction Service: Missoula
Advanced Hydrologic Prediction Service: Missoula: Clark Fork River at St. Regis
Advanced Hydrologic Prediction Service: Missoula: Blackfoot River near Bonner
Check out the kayak shop on the hip strip, Higgins just south of the river on the east side. The name changed and since I'm not a yakker I don't know it. You can probably hook up with some boaters there, or by playing around the wave. It's still early here for most, but I saw some yaks on cars downtown today and more and more people are getting out. If you want to get out now, I'd go talk people up at the kayak shop. Once the main season hits, it'll be easy to just go to put-ins and jump in with others.