The seller seems to know what he's got, as opposed to the clueless seller that often doesn't yet still wants way too much. I think it's worth checking out, assuming the frame is straight, undented, uncracked, etc.
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1989 Schwinn Paramount OS
1980 Mclean/Silk Hope Sport Touring
1983 Bianchi pista
1976 Fuji Feather track
1979 raleigh track
"I've consulted my sources and I'm pretty sure your derailleur does not exist"