all of the above is good stuff .....!
Just to expand on the mention of rocker arm movement;
If it hasn't run since 1978, then assume
at least one or more valves could be stuck ..... before you go
cranking on the motor at all, ensure that all valves can move first.
Maybe even remove & clean the rocker assembly and check each valve stem for movement and inspect pushrods.
A little penetrant soaking in for a while and a little persuasion at the valve stem
can reveal a problem before it is magnified by cranking.
