[geezer#99]

Experiment!!
Get it warmed right up.
Loosen the dizzy a touch.
Just enough that it is barely easy to move.
Go for a test drive, find a slight hill to drive up in high gear at 30 mph.
Advance your timing until you hear pinging.
Turn your idle back down to 600 rpm.
Then put your timing light on it to see what it reads.
That will be your maximum initial timing.

You might be suprised what number you get.