I woldn't worry much about one piece cranks, unless you demand low weight. One piece cranks are generally very durable, easily serviced, inexpensive, and IMO often a more attractive option for some riders than aluminum. If you want "good" bearings for them, just bite the bullet and spend $15 on some BMX-marketed ones. Unless they're seized or grinding, I wouldn't even bother. There are plenty of chainwheel sizes available in both steel and aluminum, and if you want something that'll accept "high-end" chainrings, spiders are available often drilled to accept two different sizes. The BMX market is a wellspring of very durable, pretty, and often inexpensive options in this area.
Unless you got a hard-on for fixed gear, it might be simpler to leave it as a coaster brake. If you want a bit more performance, get some good high-pressure slicks. Also, perhaps some flat, northroad (inverted or upright), or even drop bars, a new saddle, and a front caliper brake would also provide some tricked-out racy edge.
A Schwinn frame might bring more sale value, but probably little else. Cosmetically, I like the "seamless" look of those old Schwinn electroforged frames. I've also seen some nice AMF labelled cantilever frame variations, where the two seatstays continue to arc to the top of the headtube and a single larger tube takes the unusual curve to the downtube.
Some of the prettiest cantilever frames are actually being produced today. My LBS carries some stunning Nirve cruisers with very nice cantilever frame variations.
Last edited by shecky; 03-27-04 at 11:50 AM.