Interesting to learn about the Camaro misshap, but without 3D files and the original tooling models gone, it's indeed not as easy as it sounds, to perform mods, also since the breakdown of the body tooling-wise show that this version was never even taken into consideration, otherwise the front-upper would've been tooled as part of the front clip from day one.
For the Mustang it would be much easier to do the front clip as a separate part, (per OEM ) with chrome headlamp buckets and clear lenses, making the tail-lamps separate is no brain surgery ether , but even though this car is a (and I quote Tim) "Modern Day 1955 Chevy" it looks like Round-2 doesn't see any ROI in upgrading the tool.
Maybe a trauma from seeing all those Camaro, Firebird, Corvette, Viper and yes Mustang kits in sale bins at Toy Liquidators, back in the day