If you tap all 4 cylinders, you'll need 4 vacuum check valves, or else you'll get cross flow and horrible power, even though the cross flow between the runners will be small. Since the manifold vacuum should be relatively equal assuming you properly balance all the throttle plates, I would say just tap one and let the map read that, tap another one for your brake booster, and plumb your PCV, and your valve cover vents into the tube leading up to your airbox. Or, if you use a CAI, plumb the valve cover vent to the CAI, and find a way to plumb the PCV into the air box or airbox backing plate. The alternative to all of this is to say screw it and get a racing-type catch can setup.