Tucked in 74 Rear Bumper. All Sorts Of Wrong. I Hate it!

J Par,
That's very clever! Did you just tie it all back together with fiberglass?
So what I did was fitted up there like you did and determined I needed about 3/4 of an inch out of each side to fit nice and snug to within an eighth to a quarter of an inch... after that, I measured the whole thing measured center and then pulled back to what I felt was 1/4 of the way and try to do that evenly on both sides top and bottom to the best I could... then I put a piece of 3/4 inch wide blue tape down for what i wanted cut it out. Then I put a piece of tape on either side of that and pulled that original tape out of the center and made my cut there...
After that, to reconnected, I just used 8th inch thick trips of aluminum on the backside, drilled holes and riveted....
If you expand the picture you can see that clearly...
My thought was to always fiberglass everything in on the backside and smooth the aluminum rivets off on the face side and fill in with a little bit of fiberglass resin....
But for now, it just gives us a little bit of an industrial look which the whole car has that kind of Mad MAX vibe to it...