Went with Coy's C57's. 18x8 rear and 17x8 frt. both with 4.5 backspace. 235/40/18 and 215/40/17 all stock suspension. Switched the front to 225/45/17 to balance it out. still no problem with fitment.
Your Dart looks great with those wheels. Would you mind posting a pic from the front showing how far the front tire projects out into the fender? I'm trying to determine what backspace will allow me to tuck the tire inside the fender.