What k Member do I need

OK I have a set of wheels I want to run on my 68 Barracuda. The fronts are 15x7.5 with a 4.25 backspacing. I have been told that the tires will contact the sway-bar. If this is true will the later spool type k alleviate this problem because of the different sway-bar? And while I'm here maybe someone could chime in on what is the optimum width for my rear axle.I will be running 15x8.5 (same 4.25 backspace)I am cuttin down a surgrip 3.23 axle out of a roadrunner so I can go whatever.I can inboard the rear springs if needed as well.
Any input is good input, I also don't mind getting flamed for run on sentences bad punctuation or any other written language fubars