Need some help from the community out there. Even you, Mike B.! I'm replacing a short (about two feet) length of cable and two attached blocks that is the intermediary between the outside backstay & the in-hull sheet/block system.

I'm having difficulty locating the steel blocks for wire cable at svendson's and west marine, so I'm thinking about replacing the steel cable with spectra and using regular non-metal sheave blocks. I realize there would be a little stretch but at two feet of spectra, it can't be much. Should I stay with steel cable? -Thanks!