Hey, thanks for the feedback and tips. Clubman, I actually thought I had found a great option today--a double-walled Rigida w/ Maillard hub on CL for $20. Unfortunately, it turned out to be 700c size. This is from my '82 Trek 412, and I am trying to keep the thing as close as possible. Also, when I tried to bend the rim of the MA 40 back today, one edge actually cracked, and it's now officially toast. The tire I have on is actually a very lightly used, original Michelin, as well, so I'm just hoping I can swap everything over but the rim.

The rear spacing, I'm fairly certain is 126 mm (6-sp Suntour freewheel, unaltered); front is a double-walled Rigida rim, which is why I'm sticking with the double-walled. They also just seem much nicer than some of the other 27" wheels I've had (most of which were box-rim and single-walled).

Anyway, thanks for the feedback. CV-6, thanks for the ERD and the link to spocalc. I had forgot about that. I'll hunt around for a rim that might match.