on collath pics it looks like the base diameter is bigger than the 10,75x68 round. would not be surprised if the basic case is actually the 450 NE. I hope that collath comes back and is giving the base/rim diameter of his rounds. when its made from a 8x50R mannlicher basic case the 9,3x53R Finish would indeed be a good start.
problem is that I have to look then for 10,75 and a 11,15mm(for the franz sodia rifle)with this base diameter