I don't generally like to just dump links, but I found this researcher's papers to be interesting reads:
https://www.researchgate.net/profile/Fanhua-Ma
Also a good write-up on a Miata forum:
https://forum.miata.net/vb/showthread.php?t=676260
This was also on topic:
https://www.semanticscholar.org/pape...756a975ffd5f1d
I think what I'm going to do is make a window of ~1.25 lambda from 1000-2000rpm 0-500mbar manifold pressure, tapering to 1.07 lambda up to 600mbar, 1.0 lambda from 600-800 mbar, then go progressively rich at higher loads.
Reading through the above links, what I'm gathering is that in these regions, I can expect to need only 2-3° extra ignition timing for every 10% leaner I run - so at, say, 1.25 lambda 1500rpm 400mbar, I'll have an extra 6-7 degrees of ignition advance.
I don't have any flat roads nearby or access to a load dyno, so I'm basically shooting in the dark with my timing numbers.