hole in my head

Hmmm how long did the eng run before it lost the freeze plug.

I say get a accurate depth of that small hole(I don't think is as deep as you might think)

Throw it back together and run it!!!!

If it don't work like you want, buy a new head and install the comp cam.

I agree that it's had a lot shaved/cut off the head and it would be a GOOD idea to have it sonic check for deck thickness.
Where that pit is, was there before it was angle milled, and mite hold up for sometime yet.

Call a machine shop and see how much it would cast to have the thickness checked.