The Sunrace shifter came with a new rear (plastic) cable housing and new cables, so I'm ok there. Sounds like it's going to be all about alignment (in plane and in/out starty point and steps inboard). I'm assuming the 1985 derailleur has adequate alignment stiffness and the derailleurs didn't get appreciably better with indexing such that I need to get a newer / better one than the 1985non-index setup version on my Trek 460.