serpentine belt dress up kits

Don't mean to hijack the thread, but my question is kinda along the same line, I'm getting all pulleys installed, alternator lined up with spacers, etc. Does the pulley size matter in regards to ratio? I bought belts that are supposed to fit my car, but they don't. I'm running a 408 stroker, eddy rpm heads, a square back alt, eddy water pump, federal ps pump. I have a champion rad and dual electric fans from a contour. I'd like to eventually change the alt to a smaller nicer fitting one, and a serpentine pulley set up, but for now I just want to get er running.

Yes, the pulley sizes absolutely matter for ratio. The diameter of the pulleys is literally what sets the ratio.