It exhaust guide is taller because it doesn't come with a seal from the factory. They will have to lower it to match the intake, then cut it. If you're going to re use stock exhaust valves don't put seals on the exhaust. Although it would be WELL worth it to have the stock valves backcut if you are going to reuse them. Getting rid of that ski jump is a great way to increase flow. Also see if you have the budget to get them top open the bowls up while they're doing the valve job. That's just free horsepower and throttle response. It's amazing how much iron the factory left hanging out in the way of the valve.
If you ever plan up getting a bigger cam, now it the time to have them measure and possibly lower both of them. (wouldn't be a bad idea to narrow the pedestals if you ever want to upgrade to roller rockers too).
If there's anything you want to do to these heads that require metal chips, now is the time to do it.
