Still hesitates off throttle...

Try the middle hole first and see if that clears up your hesitation. If it's reduced but still there, try the outer hole. "Inner" and "outer" are with reference to the throttle shaft, so yes, the outermost hole is nearest the passenger side of the car. Note that most of today's gasoline contains ethanol as an oxygenate, which leans out any fixed fuel-air mixture. That means an accelerator pump setting that might have been adequate with pure gasoline might not be enough with the oxygenated fuel and you may have to dial in a larger pump shot than called for in the original specs. Make sure to check and correct your bowl vent adjustment after getting the accelerator pump to work the way you want, or else you'll cost yourself unnecessary gas money (refer to those linked carb manuals).

Most of the pre-'72-type vacuum advances are not adjustable.Yes, 8" of vacuum is within the active range. This very old (2005) post lists the characteristics of some Slant-6 vacuum advance units.