I do not believe that there is a "standard" measurement for the valve stem height above the keeper. I would imagine that specific measurement would be kind of irrelevant as long as everything else was correct. Let me explain myself. If the height of the top of the valve is where it is supposed to be, then whatever the spring/retainer/lock combo is doing does not really matter as long as the springs are at the correct installed height and you have the correct spring pressures, and nothing on that retainer interferes with the rocker arms or anything else. I would imagine that what you are seeing is two heads that have either a little bit different valves, the location of the keepers on one is a bit taller than on the other one, the retainers are a little different, where one set of retainers is just taller than the other, or the keepers themselves could be different, again one set of keepers is taller than the other. It is very hard to tell from that photo what is different, but it seems that you may have keepers that have additional height on them, or somehow the valves have the groves in a different location. With more information we could figure this out. If these are 2 completely different heads, built with completely different components, this is probably not that strange to see. If you moved your old valves, springs, retainers, and locks from the bad head to this new head you would probably not be seeing this. It looks like the head that is painted orange on the inside of it was set up for a higher than stock lift cam and someone needed room to get taller springs in there, and that is why you are seeing the retainer closer to the top of the valve. If you do not know the provenance of that head I would disassemble one spring on it and take measurements and compare it to the stock head. As long as they did not use longer valves on that head, everything should work correctly with stock rocker arms. Being that you have a ticking noise, that means that you probably have excess clearance, so that would negate the issue of longer valves. Did you check all the pushrods? Maybe you have a bent pushrod? Maybe the ticking is from a lifter and not the rocker arm?
