Squib,
Just buy a .280 Remington, with hi quality ammo, and you are there. No big mystery.
I don't handload, but if you want a little more oomph than the factory rounds, then just handload them up a bit.
No reason to re-invent the wheel.
Best, Mannyrock
P.S.- On the other hand, if you love to handload, then just get a new 7mm Mauser, and you are there.