The main thing you need to concern yourself with is that you get a kit that will work with the size AR drivers that you're refoaming. AR had some pretty funny ideas when it came to measureing there woofers. This is first and formost the most critical issue you need to concern yourself with. There is nothing worst than getting surrounds that don't fit properly. Trust me you don't want to go there. I'm not sure if the 10" surrounds from PE would work with those AR drivers. They're pretty much a generic replacement. Myself, I would stick with "vintage-ar" who knows AR verywell and speacializes in them almost exclusively. He'll even throw in new putty for when you go to reinstall the drivers for a proper seal. Whether you decide to go the shim, or shimless method just take it slow and take it easy. AR woofers are very well made and for the most part don't require shimming they are just so well made that they just naturally want to center themselves. You will find how well made once you get them up and running. There are few speakers in it's size that can do what the average AR spaeker can.