I have a 72 Skylark with a modified 350, I already have an MSD6A box to run with my ignition. I have purchased a used HEI distributor but I am wondering if this is the way to go because of its bulky size. So I am tapping into this very knowledgable board to find out what would be best for me. I am also curious about the use of the vacuum advance on the HEI, how adjustable is it? Thanks Tim