As already mentioned, your best bet is to simply post in the parts wanted section here. I am sure their are a few members who are parting E body convertibles
that are too rusty to build , or have left overs from previous projects .
The chance of finding a junk yard with an E body convertible would be about zero I would imagine , although if anybody had one in a yard, it would probably be Stephens Performance since he is the biggest Mopar salvage operation on Earth.

Greg