Thanks, again, for all the kind words. Sadly, I don't have access to a media blaster, so I'm somewhat limited in my options. Here are some pictures of the parts after being refinished:
The biggest issue that jumps out to me is the inconsistent bevel beneath the front lugs. I think I could fix it, but I would rather just live with it (for now, at least...).
Here are some pictures of all the parts I refinished:
I coated an upper (a Brownell's/NDS), the lower, a trigger guard, a charging handle, a six-position (heresy!) buffer tube, and a magazine button and A2 port door (both not shown) in greyish black flat Norrell's. I'm going with a GUU-5/P style carbine, so I have a Fulton slickside upper and flat slip ring en route that will get refinished in greyish black flat, as well.
Here's a plain jane 603 clone that I refinished in greyish black flat, as well:
It, sadly, is sitting on an A2 lower, though.