I keep thinking about building up some new aluminum wheels for a SS raleigh that I love, but I haven't really had serious rust problems with the chrome so I'll leave it to another bike I find I guess.

I also made a fixie out of a 3-speed frame that was destined for the scrap yard and I put 700 wheels on it, and it's a nice ride but it looks a little off, nothing hideous and most people wouldn't really be able to put a finger on it, I reckon.

My vote would be to keep the 650A size since tires and tubes are everywhere still (or keep the existing tires if they aren't worn through). You can keep the fenders and not worry about clearance at all. The tektro dual pivot calipers that come in various lengths of reach would be good upgrades, as well as the bars and stems. If you have a bike co-op they might have a spindle you can swap out and upgrade your crank to an older alloy one.