The guidelines in the Stovebolt link is incorrect. Solid lifters and Hydraulic lifters are adjusted differently (even on the V8s) and the motor has to be "hot" before making adjustments on solid lifters. If you want the complete details, I would have to PM you because I don't have a scanner right now but I can type out the info from my 1955 Motors Manual. Let me know
"Let it idle for 30 minutes till completely warm and do the final adjustment." reading is fundamental.
And the Interwebs said "Let there be knowledge..." http://chevy.oldcarmanualproject.com/shop/1954truck/index.html http://chevy.oldcarmanualproject.com/shop/1955truck2/index.htm
All most all automotive engines have 2 pistons a TDC at the same time. If you watch the exhaust close and the intake start to open as you turn the engine over that piston will be at TDC exhaust so the one thats 1/2 way down the fireing order is on compression. Adjust it and just keep going. On your 6 it will be 1-6 2-5 3-4