305's on an 11" rim

They say your Duster has the Same wheel tubs as my 68 Barracuda.
I was able to install those 325/50-15s on 10s into my tubs with only some minor smashing, I mean reshaping on the inner walls, and rolling the lips of the outers, moving the axle back a half inch, and trimming the sheet-metal down by the rockers. Of course to fit my nostalgia wheels of choice, I had to narrow the rear end and offset the Springs.
A 325 has a section width of 12.8 on a checking rim of 70% (IIRC) or, on a 9 incher. Each inch wider rim will increase the Section Width by about .7 inch. So then the section width of a 325/50-15 on a 10incher comes to about 13.5.. I think mine was just a tad larger, but that was 20 years ago....
Now, 13.5 inches calculates out to 343 mm ...... but you can hang the outer sidewall out past the body line a tad, if you raise the back up for clearance. My car is lowered so that was not an option. Consequently, that wheel/tire assembly was a really really tight.

After I had that worked out; a 295/50-15 on a 10 was sortof easy.
A 295 measures 11.6 on a checking rim of 8 inches, so on a 10, gains about 1.4 inches, and equals ~13.0 inches and change, which calculates to a section of 330mm, so, I just pushed the wheel out with spacers and cornering is now a non-issue...... even down to 20 psi.

The point is this, whatever tire you install, it will only be the branded size, on the checking rim/wheel. If your wheel is different from the checking wheel, you will have to re-calculate for your wheels.... before you order them!
IDK the checking rim size of every tire out there, but I bet @72bluNblu has you covered.