Targa rear shelf rebuild issues

[TargaT]

Hello Targa owners, As part of my 73 targa restoration process I decided to take on the warped rear shelf. I straightened the the warped plastic surround and installed a new piece of hardboard identical to the original piece. I was pretty proud of the final product. When I finally went to install it I found the plastic surround ends did not meet up with the upper side panel covers. I had almost an inch gap on both ends. What did I do wrong? Has the plastic surround shrunk? Or did i make the replacement deck too big? I know it was identical. Did I mount it wrong?
My only solution seems to be to trim the hardboard deck to move the surround closer to the ends. If I do this though the gap between the rear window seal gets pretty big though, (2 inches without the seal in. Not sure how much of the gap the new seal will cover when I install it.

Anybody been here before?

Thanks Joe