Dan,

I don't know what you're going to end up doing about that problem. There are actually a couple of problems there. The first one is that the distance between the header and the place where the thrust tube splits is too short for your BVM pipe. You'll end up with the pipe sticking through one of the two holes. This may give you a certain amount of differential in how much thrust is coming out of one side of the outlet or the other. This may or may not be troublesome in flight, but it's moot until you figure out how to get the right down-angle. Maybe someone could machine an adapter for you?