I hope Brian ( @72bluNblu ) doesn't mind me sharing this info which was saved directly from his advice. There are a lot of really smart, experienced folks on this forum. He's absolutely one of the most generous in sharing his time and advice.
"...you can get the 5 spoke legends in a 17x8 with a 5.25" backspace, which would work up front, and also a 17x8 with a 4.5" backspace, which should work out back. You could run 225/50/17's, 235/45/17's or 245/45/17's up front with the 255/45/17's out back. You could also opt for the 17x9's with a 5" backspace out back to squeeze the tire..."
He was referring to these wheels: https://www.summitracing.com/parts/vsw-141h7885gm0
Even if you don't like the style (I think they're darned good looking...) the sizes and backspace will give you a good head start.
Someone correct me but the rears should be the same between my Dart Sport and your Duster but a '70 Duster might have a tiny bit less clearance in the front than a '73+ Dart... so keep that in mind.
View attachment 1715368570
I'll also mention that this was mid-way through a conversation and this does not describe the absolute maximum amount of rubber that you can run.
