Question about control arms

[cheford]

I built a 56 F100 on a 72 C10 chassie and was wondering if it would be possible to shorten the control arms to narrow the track width. I've already purchased the new modular spindles from CPP which has helped some but the tire is still quite close to the fender. Thought I'd ask this question to see if it were possible and if it would throw the geometry way out of wack. I currently have the stock 6 x15" rims but with the modular spindles they seem to rub the lower control arm when turned lock to lock.