I've had 3 Road Kings and the first things that have to go are the seat and the bars. Regarding bars, I sat on a 2014 FLHR for quite a while, getting the feel for seat and bars. Better than pre 2014, but still not what I'd call, "really good - no modifications required". The bars feel like Heritage Bars, better than before, but not for me. The seat is still not good in my opinion - I'll take a Mustang Vintage Solo w/ passenger pillion.
Check out Buckinfitch's post on his 11'' Santee mini-apes.
They look like a real good fit for someone who wants more comfort, a beefier (1.25") looking bar and a higher bar without going to 14" or 16" apes.
Regarding cams, dealer told me that new cams are similar to a 255 (but it's not a 255). More power, but I don't know how much.
Personally, I'd stay with just slip ons till (or if) you do a full Stage 1 at which time you'd install new header, A/C, tuner, header along with the slip ons and probably have it dynoed so you could get it tuned to get all the power for the money you just spent.
OK, that's my $.02 for what it's worth. Have fun with your new King.