Valve cover differences

i have a slant 6 motor I am reworking to go into a 68 valiant. The old motor in the car has a different valve cover than the one I am building. There is only 2 holes on the new valve cover which came out of a 70 dart. The old valve cover has 3 holes in the top. If I want to use the new valve cover with the old motor's Air filter housing, do i simply plug off the hosing that used to go to the old valve cover or what do I do? I guess if I had to I can always just use the old valve cover with the newer motor.

here are pictures of the rebuilt motor and the old motor valve covers.