Originally Posted by
Primitive Don
Cool, im liking the idea of just new STI shifters, cassette/freewheel and chain. So it sounds like you guys are thinking the 6 speed RD would shift to 7, guess I would just need to let the limit screws out a little?
Maybe- try it as is- it may just work.
SIS was the same pull ratio (except old Dura Ace)- it was more a matter of whether the RD had the traverse to get across all the cogs than being a 6, 7 or 8 speed derailleur.
https://www.sheldonbrown.com/dura-ace.html