No worries, I figured that's probably why you wanted to keep the go-wing!
Since your trunk lid is already painted I'd be more inclined to buy a different lid if you wanted to run the ducktail, buying another lid would be cheaper than the welding/bodywork needed to fill the holes on the other one. Heck here's one in Florida
1971 1972 1973 1974 Plymouth Duster Trunk Lid Used | eBay
And hey, it's your car so you can do whatever you like. I thought about making a T/A hood for my Duster (Demon tribute), but I have one for my Challenger. The Challenger will have the T/A hood, ducktail and probably T/A stripes, but that's probably where I'll stop. The side exhaust reduces ground clearance (the T/A and AAR cars were actually raised in the back) so as much as I like the side exhaust I don't think I'll run that on any of my cars because they sit too low to be giving up clearance.