Tire and wheel recommendations **Sorry..another wheel thread**

[Tim240Z]

My tires need to be replaced (not because they are worn out, but rather because the rubber is old and is splitting and cracking). Well, since I need 4 new tires, I want to replace the rims too. The truck is a 71 C20 with stock 16" rims.
I read through the sticky thread with a bunch of wheel pictures, but the vast majority are either 15" or on trucks that have been lowered (a lot).

So....on to my question:
What would be the best stock(ish) replacement? I am not going to lower the truck (ever), and I want to put on the tallest tire for gearing reasons (4.11:1 rear).
So I am thinking 17 inch rims will give me the best options for taller tires (15" won't fit over the calipers afaik).
So...what backspacing and width would be ideal?
What size tire would be best? I was thinking 275/70-17s?
Here is a photo of the truck now (you can see the need for decent rims and tires!!)

Sorry for another wheel and tire post, but I cannot find anything pertinent?
Thanks,
Tim