What your talking about is a wildcat cartridge. This will require necking down, perhaps reaming the neck out, and turning the neck down and fire forming the case. And if the shoulder needs to be modified this becomes a PIA to fire form.
I had a 6mm catbird ( based on the 270 case) made and wish I hadn't had it done. Way to much hoopla to form cases.
The gun performs well but not that much better than a 243 AI. I did it because of all the 6MM bullet selection.
I would advise you talk to a custom rifle maker about it and compare it to the
6.5-284 win. Ballistics for it are impressive. Then you would be able to have a short action instead of a long action. Hornaday loads cartridge for that caliber, it's not a wildcat anymore.