The only thing they mention about the head is the increased valve size, and they don't actually give any specs. (Ford I: 1.73", E: 1.5")
There would have to be porting of some sort to use these valves. Article is a little 'light' on information in critical areas. Either the author didn't know to ask, or the shop is being secretive. Still, 300 horses is nothing to sneeze at.
