Hi Colin, Not sure on the heads, but I am sure one of the tech wizards on this thread will be able to help you there.
Use the break in shim for sure - especially on the 5 and 7 Ports. I believe the new 3 Port Race is not quite as tight. I have broken in two 5 Ports and the shim makes it sooooo much easier to start and initially tune. Leave the shim in for around 20 tanks or so. You will feel when the motor loosens up some.
Doesn't hurt to seal the motors up. Back plate, pinch bolt ends and around the carb neck