When I had my 70 Fury buckets recovered I purposely omitted the chrome bars. On hot days, the bars get very hot in the sun and I had burnt my back a couple of times. My rear seats were still in great condition and didn't need recovering so the rear backrest still has the factory installed bars. So far nobody has noticed.
Anyhow, when I was getting the front buckets redone I came across a bag of about 5 or 6 NOS bars complete with the special backing plates at a swap meet. Today I looked in my parts boxes with no luck. I will dig deeper but it's been 10 plus years since I last saw them so they may have been lost. I did however find a picture of the bag I bought. I'll let you know if I find them.