Not a ton of photo-worthy progress going into the weekend, but quite a bit of work has been done:

I got the corrosion on the window/door insert cleaned off, and thankfully, not much pitting in the metal. A wire brush on the Dremel at 10000 rpm didn’t seem to do much; I had much better luck with a foam sanding block with its fine grit, then gone over with some fine steel wool.
I had a can of inexpensive light-gray primer here, which was perfect as it was thin and didn’t risk obliterating the embossed detail. The stamped car numbers were in relatively good shape, so I masked those off to preserve them.
Finding a good match for the original Lionel “cream” paint was tough. I contemplated ordering a can or jar from Trainenamels.com, but the cost was prohibitive ($10/can or $9/jar plus $15 shipping), so I headed out to see if anything was available on the box-store paint racks. Most of the paints that were close were tinted to match the “almond” color of appliances. The Lionel color has a bit more yellow in it. I eventually found a can of Rust-Oleum “Ultra Cover” (327944 Satin Ivory Silk) that seemed close enough, especially if the lid was a true sample of the contents. I haven’t had the best luck with spray paint of late, but figured if it didn’t work, I could just clean it off and start over. Two light coats on the exterior, one light coat on the interior, then five hours under the heat lamp.
I had purchased a set of 600/601/602 decals years ago for this project, and I actually managed to find them without too much digging. Matter of fact, I actually found two sets (further evidence of an ongoing problem of duplicate purchases at train meets or online). For now, all I needed was one “OBSERVATION” line, so that was easily cut from the set and applied using a bit of MicroSol. The font is a bit off from the original, but good enough for what I’m doing. Once that dried, I gave the whole thing a shot of ModelMaster clear gloss, hoping that might add a bit of protection for the future. If you look closely at the car numbers, you can see the slight difference in tint between the original and new paint.
Lastly, I gave the car body a good scrub with some water and mild soap. Fellow tinplaters sometimes cringe at my use of water, but I’ve had no problems; the key is to get the piece thoroughly dry afterwards. I use a paper towel, then a microfiber cloth to blot up the moisture. An hour under the heat lamp assures evaporation of any residual moisture. I then gave the exterior a polish with Meguiar’s cleaner-wax. Now everything is shined up, scrapes, chips, and all.
Ready for reassembly.