That's darn near impossible to answer because of the factors involved.
Intake, exhaust, compression, heads, vacuum, and weather variables play too big of a part of it.
Every motor is going to have it's own 'fine point' with a/f ratio.
What's going to do the most justice for you is to find your best et, noting the a/f ratio and shoot for that ratio as weather conditions change.
Tuning for a specific a/f ratio or egt requires the use of a weather station and a knowledge on jet area as it relates to egt or a/f ratio.