295-50R15 Radial T/A on 15x10 Rallye

Your Duster and my 68 Barracuda share the same tubs.
295s on 10s work real good at 24psi.
But you'll need about 6 inches of bs to make it work. I narrowed my rear about 1.5 per side, so I could fit a standard 15x10, 4.5bs. Now I can run almost any catalog wheel.
My car is lowered as well, the springs having very little arch.
325s fit in there with some inner tub adjustments and a bit of lip rolling. At my ride height tho, aggressive cornering is out, while the 295s don't care..
I don't know if the spiders can be moved to ~6"bs in the 10" Rally Wheels, but I should think so.
In my case,I already had the C-body rear end, so for me it was a no-brainer to narrow it and it was cheaper than buying new wheels. I narrowed it to the max, to still be able to fit the U-bolts between the bearing houses and the springs, at their new locations with offset hangers. So when I say narrowed 1.5" per side, I am guessing a bit. That means the 6" BS is also a guess. Measure twice cut once.