Thanks for all the useful info guys. I'm converting over to BBP discs and rear axle soon, so with all that going on I don't think modifying wheel wells and spring location is on my agenda. Definitely wouldn't want anything to be rubbing either. And yes, I did hear that the Demons/Dusters had more wheel clearance.
225/60/15 up front, 245/60/15 out back if it's an A-body 8 1/4. Should give you a decent stance and shouldn't require any significant modifications.
I looked around for images on that and cars that had that combo looked awesome. However, this will be my daily driver so for practicality reasons I think I'm going to have to stick with the one tire size all around, and in a Dodge Dart, 225s shouldn't have a problem as far as rubbing or clearing?