In the long run, I believe your going to wish you had a 26 inch barrel on that magnum rifle for getting the most of what you mix up in loads.
I once did a .277 (.270 cal) on a .300 Win mag using a 26 inch tube. It shot very tight groups with 160 grain Nolser Partition bullets, under .700-MOA off the bench.
I loaded it up with 150's to hunt spead goats with years ago and my bullets were going 3180fps and shooting into groups under .775-MOA. It was a fun rifle to shoot and hunt with and different than most hunters were packing in those days. Good Luck!
