that head does look a bit shaven if im not mistaken!
Measure the "lip" between the mating surface and the start of then quench area.
Then that head mating surface has been shaved. Yamaha heads have in the order of .8mm or about .020" difference between the mating surface and the start of the quench area.
Shaving a head increases the compression ratio slightly (simply reducing the volume the trapped charge has to be squished into) but a real gain in power would come from having that head redesigned with a proper squish band and hemispherical combustion chamber.