I do have a couple Q-jet cores and I could do a mod to make one into an 850, it's an 800 now. Makes it less streetable, but it would be a good test to see if a bigger carb would help. The mod is written out in a Cliff Ruggles Q-jet book. Would be nice to try that carb from Dfish if we could get together some time.
No haven't tried open headers. I don't have much rubber left on the slicks so I don't have much testing to do before getting new ones, which I'm not sure I want to do if I'm going to quit going to the track.
Young enough to learn ... too old to remember.