Small block distributor timing??

The Distributor I have is set up for 34 degrees total advance WITHOUT the vacuum advance which is marked 8.5 degrees Do I double the 8.5 for TOTAL advance or just add 8.5.

The engine is basically a stock 360 Magnum with a knock off air gap, .500 lift 276/286 duration lift cam on a 112.5 centerline, Thermoquad, 340 Exhaust manifolds, 2000 stall converter and 3.23 gears in a Dart that weighs 3450 with me in it.