Setting the idles and fuel/air ratio

I wouldn't worry about idle speed too much. I set it as low as I can, so it doesn't want to die in "D" w/ AC on, and I go fairly lean. I recall that later cars were set to idle much faster. A boss had a new ~1974 Buick that sounded like it idled >1000 rpm in "P". I think they did that for emissions reasons, maybe because the carb was set so lean it would die in "D" otherwise. There were lots of driveability problems in brand-new cars as emission fixes were kludged onto carburetors in the late 70's and early 80's.