make sure you have 7mm and up.
check the how-to and other FAQ
http://www.contour.org/mods/mods.php?s=howtoalso 3" and 6" extension would also help.
you might also want to bring 6 autolite or motorcraft spark plugs just in case (look up info on FAQ, how-to for part #'s and direction) and plug wires, since you'd probably want to change those anyway for maintenance. when you pick up the car i'd pick up some coolant, water, oil, etc.
good luck with the purchase, and make sure you test drive it a while before heading out on your long trip.
but in any case, check the FAQ, it tells you what tools you'd need,etc.