The better way is to purchase the push rod tool that with adjust to the proper length and configuration, both end type and diameter (ball/ball, ball/cup, 5/16, 3/8 etc) most are etched with a scale to determine the change in length from nominal (ie. purchase a 10" nominal push rod and every turn is some know value) When doing so the adjusters in the rockers should be set so if the oil squirt hole is slightly above the intersection of the push rod/adjuster. Then set your preload as normal using the measuring Push rod. Now using the nominal length and the amount of adjustment added, that will be your required push rod length. It is preferable to use a test spring to run the valve thru its range of motion to ensure no issues are present and also check multiple location both int and exh.. the $37 spent on the tool is well worth it