I don't think 67 Chargers have as much rear clearance as the 68-70's because of the fender skirt design. But might be more than 66/67 Coronet/Satelites.
The front fenders I'm pretty sure won't take too much tire. Don't know if you could do 275/40/17's. 255/45/17 might be the narrowest on a 9" wide rim. You need to run about 5.5 to 5.7 backspacing (.5 spacer) to maximize the space up front.
Lefty has wide 17"or 18" tires on his 67 Coronet vert. That has the same front fender as your Charger. He would have great input on what you could fit.
Edit. Here is some info I found on Lefty's setup.
https://board.moparts.org/ubbthreads/show...rue#Post4462302Don't know if the spring are moved in.