It was the truck I had before the green stepside, a 72 Cheyenne. You can see the green truck in the background of the picture actually. It's before I ever started working on it.
17x8 all around with 5" backspace. They cleared fine, but if I'd had my choice, I'd take 4.5 backspace with the 50 series tires you're going to be running. I thought they set a tiny bit too far under the fenderwells. The wheels were originally off of a 4/6 dropped 92 model truck is why they were 5" b.s. rather than the typical 4.5 b.s.
Here's a little 97 model truck I built about 5 years ago for a local kid. Sorry about the junky picture, it was before I had a digital camera. I dropped it 5 inches in the front and 6 in the rear. Anyway, the reason I'm posting the picture is that it has 17x8 wheels all around with 5" b.s. and the same size tires you're planning on. Nitto NT450 255/50/17 in front and 275/50/17 in rear. In my opinion, the sweetest tire combo for 17 inch wheels.
You can see my old 68 short bed in the back of the picture. It was the 1st vehicle I ever did a frame off resto of and the first whole vehicle my wife ever painted.