Disc brake vacuum question

Since you have so little vacuum, either add an electric vacuum pump (later VW's & Volvos, $50 ebay used) or switch to a manual MC - 15/16"D or 7/8"D bore. The later would be cheaper, much less clutter, and most find it works fine. I like a newer 2-bolt alum MC w/ a 2-4 bolt adapter plate ($25 ebay).