yah I got a Trek 770 frame that I'm having this debate on.
The frame is in crap condition, previous owner tried to strip paint off it and its half paint
half bare steel (and no it doesn't look as good as a 1/2 polish Serotta Legend

)
I've got a complete super record gruppo to put it back in original condition (its an 83/4 model)
the only thing that really nags at me is that the frame is reported to have been a 7-11 team
training bike (and TREK list it as special team issue). I'd like to fix it but. . . .
I think provenance plays a big part in what to do with an older frame.
Marty