whistling question

I'm curious, at what rpm were you getting full advance?

It sounds like you have the large black busings in the MDS distributor which limits the mechanical advance to 18 degrees. I would put in the silver bushings and set the total at 36 degrees. That should get you to about 11 degrees initial timing. It is unlikely that cam will need more than 12 degrees initial to operate properly. If you don't have the springs and bushings to set the advance, order the MSD part number 8464.