Looks like you have been doing your homework at least, good for you. Being able to compress the lifter is not necessarily a sign of a bad lifter. I got good high quality lifters in my 355 and from new you could compress them a little bit. Your ticking noise could be from bad rockers or bad rocker balls or it could be that your lifters are not as good as they should be or a combination of any of the above. You already got the rocker covers off and you know how to adjust things well enough, it wouldn't hurt a thing for you to pull the rockers off and inspect them, look for cracks, burrs and galling. A set of long slot rockers and no gall balls is pretty cheap and if you find that your rockers are bad that maybe just the ticket for you. Also if I found a burnt valve on one head I would probably think that a valve grind on both heads was in order. The cost is minimal and a good valve grind may net you an MPG or two.