Wow, DEL, you are doing GREAT work. It looks better than the one resin '67 2DS body I've seen.
I'm planning to try one of these myself, using the top from a backbirth Monogram 1/24 '69 Camaro. I saw someone do this once to make a Supernatural 4-door, and it looked pretty good. If the top doesn't look "right enough" to suit me when I've got it on, I'll just drive on and call it a phantom '67 Impala "formal top."
Oh, BTW, do you know that there's a diecast 1/24 Supernatural Impala available? It's pretty darn nice, too--all except the top, where there's something funky going on. Yours already looks better.
Drive on!