Well, I ended up changing tactics a bit. The helm needed to start over, since the primer didn't stick (I didn't clean enough of the oil off). I sanded it all off, re-primed, and am now hand-brushing the black on.
The shield mostly did OK, but the paint flaked a little at the edges of where I masked the cross, and inside the cross a little. So now I'm going back over the sprays with brush-on paints there too.
I should have both ready for DoK.