So with everything put back together again, jacked up needle and all, I got it back on the bike, and she fired up like nothing had ever happened. I let it warm up, verified that it idled without the choke after a minute or two, and took her for a ride. Knowing I have a messed up needle may be inducing some bias in the testing, but the fueling feels a little odd now. Nothing I can really put my finger on, but that's getting replaced, so we'll see. I've also noticed that it pops a good bit on deceleration/engine braking. It's not terribly annoying, and I might just be noticing it now because I usually ride with earbuds in place. Should I just hold judgement on this thing until I get the needle replaced? Thanks to everyone for chiming in on yet another of my little projects.
"The impossible often has a kind of integrity which the merely improbable lacks."