The ATR gate sucks, yes.
Headers - plug access is good other than #1, which is a bitch. Get yourself a custom wrench to get it out, it's fine. Use a heat shield of some sort on the plug wire, I like Taylor's boot covers.
The cam John listed is good, if you want a bit more for a max effort combo, the 09-422 is what I used. McCoy is using similar stuff in his builds, like 212 duration, .500 or so lift. I tuned a truck with one, seemed a bit more responsive than my truck, very nice street manners. Could have just been the motor was fresh, dunno.