It probably won't fit, as the braze-on tab will be in the way. The derailleur can't be modified to fit, but according to Velobase you can get a 600EX (not Arabesque) derailleur for braze-on...
@JesperXT started
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It probably won't fit, as the braze-on tab will be in the way. The derailleur can't be modified to fit, but according to Velobase you can get a 600EX (not Arabesque) derailleur for braze-on...