I don't have a Whitestar game, but does it have a 3 pin plug by the coin door for a dollar bill validator? Easiest thing to do would be just add a connector and hook it up there to get your 12V. That's where all the pre-made kits plug in.
Also those cheap little plastic solderless connectors are the devil. I would recommend just soldering strips together rather than dealing with those little nightmares.