I suspect the main reason for a wide LSA for OEM is emissions related. The more overlap, the more time there is for unburned hydrocarbons to find their way into the exhaust, either thru reversion or low rpm misfire.

On my Commander 950 Pro TBI, I went A/N to 1800 RPM to get the idle to behave with an MP509 cam. Depending on the weather, closed loop it would chase the target AFR until it quit. At idle 76 deg of overlap misses a bunch. Every time it misfired, the ECM saw that as a lean condition (no fire, all the O2 in the cylinder goes in the exhaust) and just kept adding fuel until it loaded up and quit. Unless of course the cause of the misfire was a lung full of reversion exhaust which the ECM reads as pig rich (no O2) and cuts the fuel for next time. The end result is the same, the ECM chases it's tail until the engine just quits.

We could have set it to run open loop but as I recall the fuel map resolution wasn't good enough to make that work very well. If the new Holley systems have more resolution, this is likely an option but I don't see that it is much different than A/N when all is said and done.

Kevin