grant40:

I also volunteer at a co-op rebuilding bikes. Firenzes have a bad name for a reason. At least some of them were worse than regular box-store bikes. The few I have seen looked pretty terrible, but somebody above says the later models were a little better.

I would be more afraid of one that looked new than one that had been ridden a lot--if it lasted this long without falling apart then the frame is probably not going to just collapse.

If you're rebuilding bikes at a local co-op then you're probably around the 90th percentile of practical knowledge about crappy bikes on this forum. If you really want to do this then inspect carefully as you disassemble and use your judgment.