Late to the game, but glad to hear Red figured it out with Faron's advice. I have also seen a quick curve bounce right at idle, however your "all in at 2900" makes me wonder if you had once spring tab bent, or a wrong spring that left slack in the spring then let it initially jump and then slow the curve down. Because 2900 is not a very fast curve.
That being said, to jump in the curve conversation, in the EFI world, ignition tuning is often as effective in drivability as fuel management. I almost said MORE effective, but you can do some fancy stuff with injector timing and change street behavior. Having ignition control by RPM, temp, load, and wide range of other inputs, can be dramatic when on the street, but almost have zero effect when you have your foot mashed to the cowl. Although a street distributor will not have nearly the control, you do have RPM and load inputs through both advance mechanisms. Mileage is of course one benefit, but part throttle tuning is what makes you happy to take that ride in your hot rod with a coffee between your legs and/or roll on and light them up without being fussy.
I agree with Barry's comment about rocker geometry. You can go 200K miles with good build and stock or marginal rocker geometry, certainly doesn't mean ignore it. Although this thread made me think a little about a locked out timing combined with ported manifold vacuum, another way to skin the cat, or a combo, sort of like an early Pontiac approach (very little mechanical and Q-jet ported vacuum to make up the difference (Behaves differently than a Holley ported source). I don't think I like locked distributor with vacuum, but never tried it and I know I dislike the Pontiac approach as I just had to undo a mild 67 GTO and follow a traditional timing curve approach.
I can't argue with anyone's success, but I would ask what the intended benefit of taking the curve away would be on a street strip car? Seems to me if you are trying to get ahead of a slow burn, whether lean, chamber or cam induced, at varying loads or RPM you are going to have too much advance.
Red - As far as the rotor/button, Jay likely gave you the right answer. I had a string of BBC/SBCs that a hot rod club in Vegas had the same issues. They ran Mallory stuff, but we had a run of a few that the rotor tang didn't contact the cap well. Bent it up by hand to make the cap push it down, and they lived happy lives. Almost too easy to fix, hope that is your issue. However, I would add that plugs gaps too large, "power towers" and other things that introduce resistance will also contribute.
