It depends on the head gasket design. The conventional wisdom way back when these engines were new was to warm the engine up to normal operating temperature, do a hot retorque on the head bolts, and readjust the valves hot. Some of the newer head gaskets claim to be "no-retorque" types, but since the head bolts on a stovebolt 6 are so easy to reach, I'll usually do a hot retorque anyway.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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