I thought I had updated this but apparently not. So... The first rides lasts season weren't a complete success. The front brakes still squealed for one thing! I also wasn't all that impressed with the rear brake, it felt very soft and didn't have much power. The seat feels fine though so the seat post will stay. The tensioner I bought doesn't have enough travel to work with this bike's chainline, so I replaced the plastic derailluer with an old Suntour Sprint. I also put the alloy bars on it even though they're a bit narrower than I'd like. The stock ones were rusting already...
For the rear brake braze ons, I ended up reinstalling the stock brakes and running a cable between them so they don't just flop around. I could have sworn I took pics and posted this update already! Maybe I'll add pics later, but for now you can just imagine the same bike with fake brakes and a better derailluer.
I spent an afternoon tweaking a few things over the winter, but never rode it again until this afternoon. I was wheeling at around in the garage and decided to take a quick spin. Holy cow, the tweaks made a huge difference. The front brakes don't squeal, but what really shocked me was the rear brake. It's still a little softer than I like, but I can lock the rear wheel with it now. That was surprising.
Over all, I'm pretty happy with it now. It rides smoother than I imagined it would, and the five speed hub seems to have a pretty good range of gears. One of these days I'll have to take it out for a longer ride and see how it works in the real world.