I have a 58 235 in a 54 1/2 ton. The fumes from the road draft tube get bad in my garage and when the truck is sitting still at idle. I would like to plug off the road draft tube and put a pcv valve system in it. I think this would cure the problem. I have a 2-1 offy manifold that has a spot for a fitting to direct manifold vacuum and currently a twist- on breather in the valve cover. Has anybody done this and if so what can you suggest? thanks