I can feel your frustration man, but lets get back to the basics here.
loosen till clatter, then a 1/4 turn. Thats it put valve covers on and drive the thing, it might just fix itself.
A few stubburn lifters not wanting to collaspe after you pumped them up, nothing like a few thousand DRIVING rpms to get the juices flowing. Now I would'nt go out and redline the thing but just a causal crusie varying the rpms a bit.
Fotget about thinking that the spring pressurre isin adequent or weak and not over riding the lifters. the springs are plenty stout enough to do that when the lifter is working properly.
If the lifter wont collaspe I.E. working as a solid lifter then yes it will be override the spring and cause that cylinder to loose compression, but let it run and or drive it and eventually the stubburn lifters will give way then you can take the valves covers off again and do the adjustment once more, and hopefully be done with it.
Also like prevously mentioned, slick looking aluminum valve covers and performance cams will not be all nice and quiet like an oem peice will ever be, so keep that in mind, alittle valve noise should be expected.
Goodluck, Charles