I can tell you these guys are smarter than me and I think you have been given good advice. I give you my thoughts. Like Rob said should only have about two or three threads showing if more push rods too short. With the cam on base circle I spin push rod with my fingers and when I feel resistance I go half a turn and lock it down. This should be zero lash. Rotate engine by hand and watch rockers cycle and make sure they aren't hitting retainer on the valves. If rockers are hitting retainers that could be the noise. I really advise you find what is causing the noise and not drive until you do. Could be very costly. Bill