A little clarification on adjusting idle air mixture on eddy carb

You mean leaner or richer? I thought once the best vacuum was obtained you richen it up just a hair?
If you're working in Drive, I'd go for best vacuum and leave it at that. It showing strongest pull with load. can't ask for better than that
So about 13 in/hg is ideal?
Depends on the combination. Don't shoot for a number, adjust for the best you can get.