It's a lot simpler just to watch the #6 cylinder valves. The exhaust valve is the last one in line, back by the firewall. Turn the crankshaft clockwise from the front until the exhaust valve spring is fully compressed. Continue turning until that spring relaxes and the spring just ahead of it (intake) just begins to move. The #1 cylinder (not #6) will be at TDC on the compression stroke. You can either adjust the valves on #1 at this time, or set the distributor to fire the spark plug. One turn later with #1 "rocking", #6 will be ready for a valve adjustment. The same procedure applies to cylinders 2 and 5, and 3 and 4. They're called "companion cylinders" and each pair comes to the top at the same time, one turn of the crankshaft out of phase with each other in the operation of the valves.

Back when there were real mechanics instead of parts swappers and black box changers, that principle was common knowledge.
Jerry

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