I agree with most of what's been said with the exception of the phrase "it couldn't hurt" If the head is ported by someone who doesn't really know what it is they are doing, than you could actually lose power. There is more to good headwork than simply going at it with a grinder and making the holes bigger.

That is why GOOD machinists charge what they do for their services. The first thing you need to ask anyone who is doing porting work is if they have a flow bench to actually verify what the head is actually flowing. If not than move along until you find someone with a little more experience. We aren't talking about 20 year old chevy heads here, honda heads flow pretty well stock and much of the gains from headwork doesn't come from simply enlarging the ports.