I contact Skip Echert at vintage-trek.com, and here's what he had to say:

****************************************************
Hello Jonathan -

Thanks for your note and the kind words. Interesting bike and a good
mystery.

There was a 730 in 82, offered as a frameset only. With components, it is
the 736.

The first thing to check is the SN (090597). You probably have rechecked
it, but you may want to have another look. They can be hard to read. Clean
it well and use lots of light at various angles.

It may be that the 730 frameset had some residual interest and Trek brought
it back. In the paper serial number listing, the entry for the run of 8
bikes below the two runs of 730s is noted with "Track bikes for 7-11 team -
T.S.I." It may be the 730 runs were for 7-11 as well? Hmmmm

Are the Campy hubs Record or Nuovo Tipo? If Record, they may be all that is
left of the original full race components. Nuovo Tipo were used on the
1982 730. Yes, the mix of other components does suggest parts were removed,
if it was originally sold as a complete bike.

Still a mystery.

Cheers,

Skip
Vintage-Trek.com
********************************************************

Now I have two additional questions:
1. What is the 7-11 team?
2. How can I tell if the hubs are Nuovo Tipo or Record? Will I need to post photos? The tires are 700cx28. Do typical racing rims support tires as wide as a 28? And does the fact that they're 700c's mean that they were added later, since most bikes back in '83 used 27inch wheels?

Also, can somebody post the hierarchy for Reynolds 531? I found it once on this site but can't find it again, all I remember is that 531c was in the middle of five (I think) different qualities/weights of 531 tubing.

Thanks,
Jonathan