Looks like I good start, but I think you could expand the temperature range a bit in both directions. I spent about a month on the AT from Springer to mid-VA, from late May to late June. My suggestions…
As you proposed, I don't think you'll need the RR convertible pants if you're on the southern end in May/June. I'd replace them NB running tights. Coupled with the chaps, you'll do just fine. And the tights will probably pack smaller.
I'd use the running shorts as your dailywear. I've used tiny running shorts with the built-in liners, and also cut out the liners and used spandex boxer-briefs underneath for less chafing. See what works for you.
I'm not sure how warm the Under Armor shirt is, but having 1 more layer came in handy for me. I'd suggest something like a Montbell insulated vest.
I'd recommend a poofier, warmer hat that'll probably only cost you about .2-.5oz. A cheap knit cap should work fine. My last suggestion is to add a basic pair of fleece gloves. You can probably find a pair for less than 1oz at your local Wal-Mart. These can be very helpful if you need to push the temps a little bit.
It looks great, though. The hard part is waiting until May :)
-Mark