Hi Ralph,
Have two duplicates, one matching your want list with a Sovereign 350 back (looks to me like the apple-green variety), which I can part with for $80. Sharp corners, good picture and registration, a little miscentered to the bottom. The other's a Sweet Cap 350 back (SGC 50, can provide scans and price if you're interested). Price includes delivery and paypal fees. Scans below, and e-mail sent as well.
Best of luck on your back run,
--S
