Are they flush it is there any stick out?
I'd be inclined (worse case) send it to the machine shop and have them redo that head, and put it in the mill and drill out the bad ones, a common process.
Measure your piston in the hole depth while off and have em cc it and shave the head while there.
I mean this one ran ok on there all this time, right? So you know it most likely ain't cracked, etc.
You will probably come out ahead money wise, especially if that replacement head has to be shipped. I've bought several parts this year where shipping was as much (and on a couple, more)$$ than the price of the part itself.
