Rear quarter body help needed

I don't want to hijack this post but it contains good info that I can use (or unfortunately for the OP, not use) Does 3M have a "debonding" procedure? Surely they've tried it. I would think heat would cause warpage.
I have a 64 Valiant that needs the same panels so do you guys recommend a lap joint horizontally and NOT butt welded?
P.S. I love my MIG and have the panels.

I believe 3m suggests heating the panel to 400 degrees with no open flame and peel apart. I have always liked flanging a weld instead of butt welding. I used to work at a restoration shop and the owner insisted that we always butt weld. I never wanted to see how it would hold up in another collision. I have always used an air flange tool and then welding the inside so you cannot detect the seam.