That is quite a game changer! I have never made pinch pleat drapes but if I was going to, I think the first thing I' d do is look at the hanging hardware. Are they going to use those metal thingies that push up the pleat and have the little hook for hanging? That will help you decide how much fabric you need for the hardware. Will you need to use that wide tape stuff at the top for stability and putting different hooks in? Good luck with your adventure and make sure the price is adjusted for the work involved.