10" on a stock 73 Duster?

just to re-itterate;
I know for a fact that 295/50-15s on 10s will fit into/inside/between the inner and outer walls of the tubs, at almost any ride-height. I say almost because there is a bulge out near the top of the wheel opening, that can contact the outer sidewall when the tire, on jounce, moves up into that area . So I mean if you intend to jump your car, or if your springs allow a lotta body-roll, you gotta keep that in mind....... lol.

But on the factory-width A-body rear-end,
> it will take a custom backspace wheel that IMO looks poorly because the spider is out so far; Here's a guess/6.5". AND
> more than likely, the springs will have to be moved inboard, which is really not that big a deal, and when you do it, you can simultaneously correct your pinion-angle, and move the axle back a tad. AND
on my Barracuda, I had to trim the outer wheel house lip. Actually, I just folded it up a lil
>So then, to use any common 10" Period wheel, which mostly come in a nice 4.5bs, the rear end has to be narrowed some 2 inches per side, AND the springs moved. After I did this, the tubs even accepted 325/50-15s
I can almost guarantee you, that after you do this, you will never be sorry. Especially if you have a 360 or a stout 340, which will just burn up 275s at the rate of one pair every summer, if they even make it that far.
Furthermore, when you are powersliding on city streets, 275s do not have enough sideways rubber for a controlled slide, AND they don't have enough sideways rubber to brake if you lift throttle. Thus, there is an excellent chance that you will spin out, if you do stoopid stuff. In traffic, this is more than just embarrassing. Whereas:
295/50-15 BFG/Cobras are very predictable below 30/35 mph. In mid-slide, if I see it going bad, I just lift throttle and let the tires bite. The car will lurch oddly then head in whatever direction the front wheels are pointing, so be alert. In worst-case, I lock everything up, and the car comes to a nice sideways sliding stop.
But if there is no saving it, I crank the steering wheel the wrong way and mash the gas, which swings the back end around until the car is pointing to where I want it to go.
Here's the deal:
with 275/60s or with 275/50s
Everything happens faster, and somewhat unpredictably, and as a 50/55 year old at the time, sometimes (many times), the car was no longer on the road, when it came to a stop. I cannot count the number of times. To say this was frustrating, doesn't even come close.
So here's what I spent;
>For the stock-width rear end;
245s on 8s, 255s on 8s, 275s/60 on 8.5s, 275/50 on she same 8.5s which were not wide enough, so I went back to 275/60s on the 8.5s; and a few broken or bent wheels; Ok that's 5 summers.
> after I narrowed the rear end:
295/50-15s on 10s, and the offset spring perches.
These tires have traction only the first few weeks, then she's into the hard stuff. After that they will slide very nice and they'll go for Three summers in total, two if you lite 'em all the time. I keep a spare set in my shop at all times.
> As you can see, narrowing the rear, in the long run was not only the right thing to do, but was also waaaaay cheaper, and above all; Safer.
BTWs,
>with discs on the front/ 10" drums on the rear, , after you do this, you can get rid of the brake-proportioning valve, and finally have some decent stopping power. and
> as your rear ride height goes up, your car will experience more body roll in the turns. This means that on one side of the car, the body will tend to move towards the inner wall, while the other side will simultaneously tend to move towards the wheel lip. If you run SS springs, your azzend will be high enough that this will not be an issue. But be warned, not everyone likes the ride of those babies. and, they will shift weight OFF the rear tires, towards the front, which even with the 340 T-bars, you will feel.

Ok, bottom line;
I'm NOT telling you that you have to narrow your rear end.
Maybe you don't drive like I do.
What I'm saying is that;
if you do drive like I do, then
for optimum tire life, and
a safe driving experience,
the best things I ever did, was to bite the bullet and narrow the rear-end, AND move the springs.

Happy HotRodding.