My google tape measure says the total width of a 67 Camaro is 72.3 in vs the total width of a G8 at 74.8 in.
I'm not that familiar with a G8 but pretty much all modern cars run a deep backspace wheel so if you put the G8 independent rear in as is then you won't have nay dish on your real wheels or as said in the previous post you would need to widen the body to use it.
If you are a talented fabricator looking for a project I say go for it.
But
There are so many well engineered options for first gens. Either bolt in subframes, 4 links and truck arms or something like an RS chassis. If I were in your shoes I'd choose the latter and focus my $$ and attention on other parts of the car.
Nice Bronco. What's the story on it.