Buy two 1/2" spacers that fit your carbs. Drill a 1/2" hole for the vacuum fitting on the rear spacer and you should be good to go. As others said, if you're pulling less than 10-12" of vacuum, you'll have a problem no matter what manifold you use. You may even be able to find a spacer with a pre-drilled and tapped hole. if you don't have the tools, send the spacer to me and do it for ya.
