You would be surprised how little it takes to do this. Slice it right next to the gap as close as possible, just an 1/8" away max. Cut it with a 1/32" thick cutoff disc and where it needs to be a little more cut that with a 1/16" disc. Tap it over from inside the gutter with a body hammer and check trunk fit. You will probably have to go back and forth a few times, widening it a little more maybe and checking it again. Then weld up the seam.
The hard part is that fender extension is over too! It's pot metal and you can grind it some to thin the end of it. You can cheat a little on the trunk lid too grinding the edge a LITTLE I mean VERY LITTLE, but you can get a tiny bit out of it too.
There is nothing I can't express more than to not try and make it perfect, unless you cut the end loose you welded on and put it straight you are going to have to get it "nice" all around instead of perfect. Don't leave the other side and the back perfect and try to make this side perfect. "Screwing up" the other side a little to make this one acceptable may be where you go with this. Remember, stock, these cars of the vintage did NOT have panels that fit like todays cars. They fit like CRAP, I have a 65 Buick Skylark that I put a LOT Of time into making the panels fit like they do now, they did NOT fit well from the factory 50 years ago.
Brian
