I dabbled a year or so ago at desiginig my own wild cat and I looked at it from a different perspective. With a Rum you alread have a nice super maginum chambering, but how can you increase it and make it more user friendly. Add a 40 degree shoulder(no brainer), less brass trimming and a slightly more efficient cartridge. So what else would benefit, my idea was to shorten the cartridge to maket it more magazine frienndly with further seated bullets, but do not change the taper so although you are fire forming the shoulder you are not fireforming the whole case. So you dont really need to consider it as a seperate step. Its a wildcat without all the trouble. Now my purpose was to reduce the caliber also.
Just my .02