I think @abodyjoe pretty well covered it, the one thing I haven't seen mentioned yet is what wheels/tires you're going to put on the car, which is really the place you need to start.
I agree, I think I'm set up for success, I'm leaning toward 17 or 18 in wheels. What wheels/backspacing are you using with the 18s, are they custom? I see Enkei on the wheels in your profile pic are those your 18s? I saw a Dart for sale locally a while back with 09+ Charger/Challenger wheels on it so that has me wondering what modern factory take-offs make a good choice? I know the backspacing/offset is not at all what these cars were designed for...
On a Dart, if you want to go bigger than 275's you'll need the 3" offset and mini-tub. But that will open you up to run all the way to 335's if you want.