I had a wideband in my '64 VW and used it to keep an eye on the twin Dellorto two barrels. Very handy tool to know exactly how lean or rich it is at various engine speeds and loads.
A big key to tuning AFR is also being able to adjust timing to suit. The leaner mixtures you'll be after at light throttle burn slower so you'll need to add in more ignition timing under those circumstances to pick up as much mpg as possible. As lean as 16-17:1 is perfectly fine under light load situations as long as you have a way to add ignition timing to start the slower burn sooner. 12.75:1 is ideal for heavy/full throttle.
This thread on the VW forum has been the biggest help for me to understand tuning carbs for the AFR targets you want under different loads. The tuning info is for Weber/Dellorto style carbs but the principles are the same no matter what carb or engine you have. Pay particular attention to the posts from john@aircooled, he is super sharp on tuning for the most mpg, cool cruise temps, drivability, and power at WOT.
https://www.thesamba.com/vw/forum/vi...c.php?t=293837