In generally, you want to have the same amount of two-row as other malts, so increase the two-row so that 1/2 of your grainbill is two-row. You could easily leave out the carapils in that recipe- you won't need it at all. But if you want great foam stability, adding in some flaked barley instead would be my preference.
As far as grainbill, I'd consider reducing the black malt and/or roasted barley. I don't use both in my oatmeal stout, as I like the Briess black malt in my oatmeal stout.
I don't use any aroma hops at all in my oatmeal stout- just the bittering hops. Normally, you want a creamy mouthfeel, with a slight roasted-grain flavor and aroma with no real hops aroma and flavor in an oatmeal stout. I think either EKG or fuggles or even willamette would be my first choice for bittering.
I like a little victory malt in my oatmeal stout for a hint of nutty/toasted flavor to the beer. That's just my own preference, though, and certainly not necessary to a good oatmeal stout!