I'm running 4.5x15 Cragar's with Firestone F560's, and probably should be 5.5" to 6" for better handling at speed, plus the only place I can get the tires is from Coker. I'd stick with the wheels you've got up front.

What's your overall diameter difference, back to front? The drop does more for the look than the width of the fronts, IMO.