Tailpipe wideband sensor is OK if you've got long straw to sample way up pipe like what is used on dynos.
Theorectical max-power is 12.5:1, but actual testing shows it's around 13.5:1 on NA engines. Boosted engines I like around 12.0:1 for some safety. Doesn't sacrifice much power compared to 12.5:1, but gets you larger safety margin.
You might want to completely clean & floss your carbs (or send them to Lord of Carbs for refurbishing). You'll most likely see even richer AFRs. Might want to go with 2 washers and 96-97 jets. You're probably in 10.5:1 range now... or richer where it stumbles.
