318 stroker - Piston itch....
The guy did some nice work for you on those 9973 heads. The thing that I was getting at is the height placement of the valves in the heads, chamber side,as the 360 heads would be deeper in the chamber than that of the 318 heads. This way if the 360 heads would have been used then the valves would have been about .100 deeper in the chambers and interference issues would have been minimal even with the 2.02 valves.
The cc's on this head has to be fairly small from the pics. as the valves reduce the chamber volume due to the margin thickness and area that they take up.