There's Harrisons Early Spares up here near Brisbane and they do plastic welding. Not sure if they can help you out with this, as I have never actually used them before; but they did say that they are able to weld driving light rings into standard grills and such, so I don't think that it would be a problem.
Harrisons Early Spares
That's one option. As to your dash lenses, it's an easy fix. You can order a replacement kit: 2 large 2 small lenses. Not sure but I think it's about $45 from GT Ford Performance
down in Victoria. That price might be just for the 2 large pieces though, I can't remember.
GT Ford Performance
OR you can get them from Mustang Auto Parts
here in Brissy. They do Falcon GT stuff too. They're not listed in their parts catalogue, but I wrote them an email and they assure me that they can get them. Pretty well same price, so I'm getting mine from there as soon as I get around to it.
Hope this helps ya out!