1983 hydraulic engine

Napa will have it. Ask for Permatex valve grinding compound. They should also have the tool with 2 suction cups (just a wood dowl with the cups on the ends)
Slant six, 99% of them that I have seen do not have a bolt on the end of the crank.
Piston at top dead center means that both valves are closed to do your leak down test. That will have to be done for each cylinder.