Carl,
When you say "backing off a smidge", in which direction of rotation of the distributor?
Everything you posted is good information/advice.
One other factor regarding the BB not being optimal: the flywheels often get swapped around over the many years. Since the markings (BB location relative to TDC) were different in many different years, the only good/consistent marking is the TDC marking (not the timing/BB marking).
For us normal hobbyists (normal?), the adjustment of timing to maximum vacuum is no doubt better (and easier to do and uses cheaper equipment) as a general practice, than other traditional techniques (standard or advance timing light), unless and until you know the best setting for your particular engine.
I advance the timing until maximum vacuum reading, then turn the opposite direction, retarding the timing that ultra-scientific smidge. A test drive under load will help one verify if one's smidge is within specs.
Great question BTW!
Carl
