Looks good to me...but if I were brewing it I'd drop the chocolate malt altogether (but that's just me...I think it throws the flavor out of balance and contributes harsh notes), and stick with some carafa (though I personally use carafa III special).
My porters also improved a great deal when I started using larger amounts of caramel malt, especially very dark caramel malts (and up to a full pind of that). German CaraAroma malt also works smashingly well in porter.
Contrary to one might expect, he caramel malts don't make the end product out of balance on the sweet end of things at all...in fact the color and roastiness that comes from the dark caramel is quite intense...and delicious.
Just opinions, that's all. In the end it all depends on what kind of flavor profile and mouthfeel you're going after.
If you were going for an historically authentic porter, you'd probably wind up with the simplest grain bill of all: all, or nearly all, brown malt.
Do you hav a favorite commercial example of the style??