Here' is one I brew, that turns out GREAT. I added some Chocolate to the boil, but you can omit that, I think it gives it a nice subtle chocolate flavor up front. I get a GREAT head on this beer that sticks around and laces the glass to the bottom. Smooth, roasty, subtle, and just tastes so good.
I think the roasted barley you have is a bit much for a porter, personally, and the 120 is a bit roasted for a porter WITH the roasted barley, personally. You aren't far off from a stout in terms of "style".
I'd also think that you'll need a bit more hops in there, 1 oz spread out till 15 minutes isn't much and the late additions aren't going to offer much, especially with that grain bill. It's all about the roasted smoothness, not the hops.
I'd toss an ounce or less of something under 10 AA in the boil at 60, and make another addition around 20-15 minutes, and make it another ounce or atleast .5 ounce of something light.
Yeast selections sounds good.
Feel free to change up my recipe. It's a pretty good one, and I wouldn't offer it up if it wasn't. It's not far from yours. The roasted barley will give it that dry-ish burnt acrid flavor that you'll find in most stouts, IMO. You could even pull the barley, and toss in some Carafa II or something even.