I'm installing a performance head on my Zetec Blacktop. In working on the cam timing, etc. (see additional posts) I found an "extra" hole on the intake side. Some internet research leads to the conclusion that is an oil galley hole and the size is 1/8" NPT. I bought 1/8" NPT plugs and they don't fit. I also took the two plugs from the back of the head to see if they would fit.... no luck.
Any ideas on what the hole pictured below is is and what I should do?