[old ugly]

i think i must have the same aftermarket shell as you.
but i have managed to cheat it some to make the gaps a bit better.
the rad cap thing is a bit annoying tho.
my car is not fancy so i just accept it. they are far from perfect, but they are shiny.

i moved the bottom ahead and the top back.
if you can move the rad down that may help. maybe it has shims lifting the rad up?
or maybe the body end of the pivot mount can go up a bit.
other than that your only choice may be to get the original shell replated.

sorry not much help answering your question.

ou