Did you miss my laughing at the end? I'm more light hearted than that now...LOL! That was my attempt at some humor.
The reason for the hole there is to get more area, better corner radius, and use the head bolt that is sticking through...to pull air to that side of the port, or tug on the air column more.
You have to run pushrod oiling rockers (like TD) and block the oil passage top and bottom plus a tad of silicone on the head bolt flange to seal that up.
