Originally Posted by francophile

First thing is not getting hung up on what's missing, and have a rough vision on one or two possible outcomes you'd like to see. What are you aiming for?

With something like this, I'd start exactly where you have: Taking good pictures. Then I'd look for a couple of comparison bikes of roughly the same year/model, normally I hit ClassicRendezvous first, then a few other places to try to find pictures I can reference for the little details. You may also hit CABE and setup an account if you're not already there, too. There's a braintrust over there, same as here.

Then I'd proceed as you have: Disassembly, down to the bottom bracket (leave headset and bottom bracket assembled, properly pop out the cotters) . I'd bag all the parts to keep them together, even the stuff that seems too rusty to do anything with, with exception of consumables you need to replace anyway (spokes, tubes, tires, bar tape etc).

A lot of the rust I'm seeing there is negligible, especially in the white painted areas. That will cut out with a good compound and/or ultra-fine brass wool gently brushed across the tubes with a diluted dish liquid as lubricant, which will also clean up the chrome nicely.

Before starting any of that work on the tubes, I'd take some construction paper and painters tape to tape the paper over any surface-mount decals with a tiny 1mm margin above/below them. This way you can pass across the tubes without any issues.

You may consider an Oxalic Acid bath as others suggest, but that may trash or fade any surface-mounted decals. I'd probably do that for the rear dropouts, but I have a little bit of beef with water-in-tubes myself, so I prefer only to do non-perforated tubes with exception of the bottom half of the BB shell.

For smaller parts, like the clamps holding the chain guard on, which are heavily rusted ... I'd scrub off any surface rust and soak those in Evap-o-Rust. It's a killer product, nobody ever believes me when I tell them what it's capable of, and it's all-natural, so no neutralizing or special handling for disposal. Best part, though, you can re-use it several times. I keep a few pickle jars around full of it and will re-use it a dozen or more times before it gets kinda funky. You may be able to salvage the bottom cup on that headset, you'd be surprised, if not, you may be able to find a replacement here or on CABE.

Once I got the frame cleaned up, I'd assess: Where are we? Does it look OK? Am I confident it's structurally sound, lug joints OK, no hardcore internal rust ? If yes, I'd proceed. If I wanted to keep the patina intact, I'd consider a going over it with semi-gloss or maybe even matte 2K clear. If the frame is in exceptionally good case, and you wanted to have a real showpiece, maybe drop the money on having it professionally repainted.

If you're not planning to restore it, I'd consider posting the frame/fork/headset/assembled BB/crank for sale here or elswhere, or give it up for the cost of shipping (I'd take it and compensate you for pack and ship). This bike is one of those things I love to get my hands on and set aside as a long-term projects slowly plug at over the course of a couple of years.