Don't get oversized valves. If you get itr valves the head will need a 3 angle valve job since the cit on the itr valves is different than the gsr ones. Don't order valves and such until you pick up a head and check it out. If you end up picking up a head that has valves and they are in good condition then use those. There really isn't too much difference when upgrading to itr valves, the money could be better spent elsewhere. Skunk 2 valves are not needed with your setup.

Get jdm itr pistons. 11.3:1 comp ratio, perfect for your setup. Get .25mm oversized.