I learned my lesson on buying assembled heads on a new pair of Darts. I won't do that again! Here is what had to be replaced after only 100 miles of driving!
Valvesprings - one damper snapped in half because valvesprings heights were not set!
Screw in studs - two snapped in half driving at max 3,000 rpm! Sounded like a branch breaking in half!
Retainers & keepers - needed to be changed to get the correct spring heights BECAUSE the seats were not ground deep enough
Shims - there were'nt any! That's okay, now I know how to setup heads.
Valve height micrometer - Thanks for the school of hard knocks, Dart
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So yeah, I reused the valves and that's it. Should have bought BARE heads and had the machinist set them up. Live and learn.
BTW.... car is bulletproof now and has made MANY passes since I rebuilt the heads.