First off, FORGET what I said about opening the doors and decks first. Noooooooo. It became apparent pretty quick that I'd have a floppy, unmanageable mess by doing that.
HOWEVER, cutting down the rear door cut-lines looked like the right way to go, as it still eliminated having to re-scribe them. During careful measuring, it began to look like that would be a good place to go across the roof panel too. I've never actually worked on one of these in 1:1, but I knew the rear outer fenders on these cars bolt on, so I started looking for photos of where the seams are, and how they're hidden. That suggested the most appropriate place to cut the rear bodies and minimize detail-loss and bodywork.
The photos show pretty clearly where I made the cuts, and the remarkable thing is that cutting as shown, the sections practically jump back together. The drip rails, side moldings and roof-line still flow with no wonkiness (if you position everything carefully) and the Chevy roof is only a small bit wider at this point than the Olds. There is sufficient thickness of material in the plastic Chevy roof section to smooth the transition.
The cuts and fill-work necessary on the rear fenders are far enough from the scribed trunk lines to avoid getting into them, and the fill on the sides of the quarters is confined to the body-line crease. I'm very happy with how this worked out, and the Olds roof section fits back into the Chevy nicely too.
Edited by Ace-Garageguy, 26 November 2012 - 04:23 PM.