Unless you want your name associated with a new cartridge there is no need to design one.
Just about every combination of case and bore size has already been tried.
Why design a 9.3 with a shortened .404 case when you can buy dies reamers and brass or loaded ammo in .375 Dakota.(There is only a .009" difference in diameter between a 9.3 and .375).
Not available at your local shop,try .375 Ruger.
Gotta have a 9.3 try 9.3x64.

If you want to design your own cartridge check out the price of one off reamers and dies and see what the resale value of your custom one off gun will be.
Want to put a .404 in a 30-06 length action? Trim the neck down by .1". Standard chamber,standard dies. Will fire factory ammo fed directly in chamber. Can be reloaded to factory specs or higher.
If you later decide to lengthen your mag or replace the bottom metal it will feed factory loads without further mods.
In 9.3 cal I find the 9.3x62 very hard to beat. Hanloaded you can get 2650fps with a 270gr Speer in a 24" barrel and 4 rounds in a standard mag. The 9.3x64 will equal H&H ballistics in a shorter package.
The .375 Ruger would be my choice as an all purpose round in an M98.( The Dakota is not as readily available).
The .404 Dakota, 416 Ruger are also good DG rounds, equal in performance to their larger counterparts.
It's when you really feel the need for greater stopping power that a wildcat is justified.
The .450G&A. .458AR, the .460 Short, the .458 Sabi (based on the shortened .500Jeffrey case), the 550 Express, and dozens of others are already designed and tested and will fit in a 30-06 length Mauser action.
But then if you want your name stamped after a number on the barrel.....