Every little bit counts. If it has removable domes, you can always bump it up. Most only run 180-185 on average any way, so going from 150 to 170 would have to help IMO, then just keep your eye out for domes to bump you higher.
Edit:After looking at it, I don't believe those domes are removable. Do you would be gaining a little compression, and possible better cooling, just a guess on that part. I've always heard the billet heads cool better than cast but I don't know for sure. For the price though it's hard to turn it down. And you never know, you might get more compression out of it, could be that he had it on a weak engine, or never really tested it.