Valve guide seals ?

[RShaips]

I need to change my valve guide seals on my truck. I have the body off the frame so now is the time to do it. I have never done this before , should I replace the O rings and also add the umbrellas seals ? I have read that you can put air into the cylinder or use a soft rope stuffed in there to keep the valves from falling, any preference? I guess all I need to change them is to buy the tool for $10.00 that will compress the spring and remove the retainer and spring and slide the old O ring off and put the new ones on. Thanks for the help.