64 Valiant 273ci noisy valve train

Yeah, not really objectionable after you know how much is normal.
Don't be tempted to decrease the lash to less than the factory specs.
Firstly; you won't find any more power.
Secondly you will find less take-off torque
Thirdly, it will probably lead to starting or idling difficulties.
.003tightern on the intake can be a disaster.
Sorry I don't have the specs for that engine