P11 front fender stays

My Dunstall Atlas project is coming along and at the moment I’m trying to sort out the front fender. I’ve purchased new Y brackets from Norton Race Parts which seem to require a 4-1/2” front fender. Unlike some Y brackets, they are ridgid and the fender must fit to them. The only beaded alloy fenders in a 4-1/2” size are quite long and in my opinion will require a rear fender stay. It crossed my mind that the P11 fender stays might do the trick. Can somebody tell me what the dimensions are of the rear stay
1. Distance between stay mounting points at sliders ( width)
2. Distance between stay mounting point at slider and mounting point at fender ( length)
3. Will the stay accommodate a 4-1/2” fender

Thanks all