Narrowed E-body Dana width?

So, I'm laying under my car (70 Cuda) contemplating on how I'm going to achieve the rim appearance I'm after when I go to different wheels, and after all is said and done the basic answer is I need a narrower diff. I "could" narrow the factory dana but I'm not really keen on that idea so I might shop for one already done at swap meets, online etc. My question is...is there a set width that people "commonly" narrow these things to or does everybody just wing it with a different number that they come up with for their car? (I'm sure of the answer I'd just like somebody to confirm my thoughts)
In my cars case, it's tubbed and the springs are moved inside of the rails so it looks like I could knock off 2" inches per side, but if I was shopping for one is there a width number that would be considered common.
I realize I can install a B-body diff but that doesn't seem like much gain for the cost or effort- but if that's what the answer is so be it.

I bought my Dana brand new as a Direct Connection piece. At that time, they sold it as a 52 1/2" wide assembly. I don't know if this ever became a standard number, but it was narrower than what came out.

Thanks!
I found one for sale that is 52" 5/8 so it's pretty damn close to yours. I guess we'll see if there is any consistency to that number as the replies come in.

I'd get the wheels/tires you want to use and mock them up in the wheelhouses and measure for width.

Can't dispute logic!