[wrndln]

What you definitely need is an original stiffener support piece that is formed correctly compared to the cheesy repros. I went through this same thing as you when I tried to use a repro lower panel, as I thought I could never find a decent original panel. It caused a large gap in the middle between the panel and my original trunk lid. After looking for a long time, I found an original lower panel that worked great and lined up perfectly with the lid, but with some TLC to make it nice again. The repro stiffeners are almost flat like you stated and made of thinner metal than the original stiffeners. They just don't work without serious effort. BTW, You need to use a vertical stiffener if you plan to use a rear spare tire bracket.

Rusty Nelson