With the rocker arm torqued in place, the lifter preload should be between around .040" and .080" on the lifter plunger. THAT will be the correct pushrod length.
To set it up for high performance, shimming each individual rocker fulcrum after that to attain .020" to .040" lifter plunger preload is prefered.
To set it up for high performance, shimming each individual rocker fulcrum after that to attain .020" to .040" lifter plunger preload is prefered.