The conventional wisdom at the time I was learning the trade (mid-1950's) was that the ball and pointer was a starting point, and for best performance/minimum detonation the timing should be tweaked a degree or two at a time until minimum noise and best performance was reached. Use the clamp screw on the distributor housing to set the initial timing to the ball/pointer position with a strobe light, then use the slotted "octane adjustment" to tweak the final setting on a road test. Get on a steady uphill pull in top gear, and listen for a ping at or near full throttle. Advance the timing until it pings, then retard it just enough to make the ping go away. At heavy load conditions, the vacuum advance shouldn't be a consideration- - - -it only comes into effect under light-throttle cruise for fuel economy. As soon as the throttle is opened to pull or accelerate, the vacuum advance goes away. It should not be necessary to use premium gas unless there's something very wrong with the timing setting. That engine only has about a 7:1 compression ratio, and regular gas is good for 8.5:1 or better.
Jerry
