This is the list of instructions that Ken was linking you to oldcar;

I have a 1959 Apache 3600 with a 235 6 cylinder, with solid lifters. I was wondering how to adjust the valves. Submitted by Kevin Clements
Here are three answers:
#1 Hydraulic Lifters -- "The adjustment of the 235's valves is real fun. You need to run the engine until it comes up to operating temperature and add about 10 minutes. (About 30 Min Total). With the valve cover off and the engine running, set the valves in any order you like. I like to start at the back and work forward. You may have to go through the valves as many as 3 times before you get what you want. You need a tappet wrench to do this job, you cannot do it with a hand wrench and screw driver. This job takes a good hour to do right."
Ted J. Welch
Editor: The Classic Truck Shop

#2 Solid Lifters -- "You never should attempt to adjust solid lifters with the truck running! This will only result in bent pushrods if one is inexperienced. The proper technique is listed in the shop manual, Warm the engine to 185 degree OIL temperature. Bring each valve to top, using a feeler gauge, wrench and screw driver, set the required gap as shown in the shop manual. The rocker castings can have as much as .005 difference between hot and cold. Using this technique you should have perfectly adjusted valves first time! Thanks!"
Jim Beidatsch
past president, Northern California Chevy/GMC Truck Club
local Chapter Coordinator, Pickups and Panels 'n Print Magazine
Norcal Truck Club

#3 General (Engine NOT running) -- "I have a trick I use every day at work to set valves on inline 6 cyl. motors. Chevrolet and John Deere firing orders are the same: 153642. Set the motor to fire on #1. Set the lash on 1E, 1I, 2I, 3E, 4I and 5E. Then rotate crankshaft one revolution. #6 should be in firing position. Set lash on #6E, 6I, 5I, 4E, 3I, 2E. Your valves are all set, and it only took about 5 or 10 minutes. Remember exhaust valves are on the ends of the head, and they look different than intake valves, so it is easy to identify the valves for cyls. 2,3,4,5. I hope this will help someone. Again, thank you!"
Carl Riemann