15x10’s on a 7.25” rear axle seems like a great recipe for 7.25” destruction. If you hook it’ll be over.
Since 15x10’s don’t really fit on a stock Dart you might want to include the modifications you’ve made to your car so we have an idea about what kind of backspace you’d even need, since you’re probably in custom wheel territory for 15’s. Which is why most guys with a 3” spring relocation and mini-tub (probably what you did?) narrow the rear axle if they run 15” wheels.
Seems to me like you should figure out what rear axle you’re going to run first. Because a 7.25” with wheels that big isn’t a good plan IMO. And since you’ll probably need to either shorten the axle or buy custom wheels, you’ll only want to do this once.