Hiredgun 97t plug should work fine as wright suggested. The shim is only to be used for break, so the engines internals aren't put thru as much stress during the break in process and to also make it easier on you. 30% nitro will be fine for break in. As faras the coolinmg head goes temps will vary from cooling head to cooling head so if you change it you will see a change in temps, But as Mugenb46 said its best to tune for smoke first and only check temps to make sure your not running over 260f.