318 heads, 302 casting. Mystery holes?? (Solved!)

I learned my hard way lesson on the air holes with an 84 D350, when I put headers on it. Fired it up, and PHTT, PHTT,PHTT....lol. Fortunately, there is 4 miles of room in a truck..so I was able to move the headers, tap the holes 1/4-20, and plug em up with allen head set screws.