If the head is shaved down flat with the rest of the surface you may want to try a higher octane that seems like it would be a lot to shave off. also do a compression test.
ok,so i did a comp test,and came back with 115. For the record the gage is old,and i don't know what brand it is,just that it says its made in the U.S.A (yes IT told me that !!)
Thats with the engine warm because iv never run a comp test before i didn know.
And it took 3-4 kicks to get to that point.