17" Coy C-5 backspace and tire questions

[WhatWouldSeanDo]

I am looking into getting some Coy C-5's for my 77 stepper. I am thinking 17x8 front and 17x9.5 rear. The front can be backspaced 4 or 4.5" and the back comes standard with a 5.5". I am selecting wheels in anticipation of a McGaughys front big break kit and 2" lowering springs (for a total 4.5" front drop) and the rear flip kit and c-notch (6" drop").

I want meaty sidewalls both for rim protection and b/c I prefer some rubber (and white letters) showing, and the widest rear tire I can easily accommodate.

I was hoping for some advice on backspacing for the front and tire selection all around. Also if anyone has pics of 17" Coys (or heck, 17" anything similar) on a square body, I'd love to see them.

[Captkaos]

This is my 87 with 17" Impala SS wheels (5.25" BS)

[WhatWouldSeanDo]

I like that a lot. Enough sidewall for me and room for big brakes. What profile are those tires 55?

[Captkaos]

They are 275/55/17's, 28.90" tall, same basic height as the factory 235/75/15's 28.87" tall