The best idea so far is the bar-end shifter. I assume that DA 9 speed or 10 speed bar ends can work with freewheels in friction mode. If so, go that way. A used set are in the $50 range. Race the piss out of the 800 until you get enough experience at speed in a pack to know what you want and if you're willing to pay for it. You've already got the "good bike". You just need to convince yourself to race it.