Brad, a special anti galling lubricant is made for aluminum. Mcmaster car or
any tool shop supply will have it. If not, I have also used PB blaster or WD40 if you have too.
If you have the ability to heat the head thoroughly, than it is a good idea. Just remember, either way you do it
you will have to ream the guides to fit the valves properly. Do you know how far to drive the guides in?