IF you're in search of "more traction" for your "healthy" engine, rather than how wide the tire is, be more concerned with how sticky the rubber is. Like seek out a V-rated tire rather than a normal "looks good" tire. There are some 17" wheel tire sizes which are very similar in "revs/mile" to some wide 15" sizes. I suspect that with the V-rated tires, you'll not need to stuff the wheelwells quite so tightly, which will then mean you can better explore the higher-speed cornering capabilities of C-body Chryslers.
CBODY67