When you get ready to service those heads, who ever you get to do them, go over every detail with them so that they will be properly prepaired to perform the work asked of them.

Exhaust heat on those valves & valve seats are the main things to think about & just any old valve or seat wont cut it.
Dont get talked into having hard high nickle content seats installed, not for a tow rig, Stellite or Carbide.
Neil