My 8 speed dura ace set up works with a 28t large cog, just barely. In the big/big combo there is very marginal chain rub, safe enough for a few pedal strokes if I accidently shift there.
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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"