Nothing wrong with either of the OP's choices...either would be just fine on elk.
I'm a small bore aficionado but recently picked up 150 of the old style (amber colored plastic box) 200 grain .308 Grand Slams. They'll straight up knock an elk's dick in the dirt based on past experiences...
I'll be turning my .300 Win Mag into a .300 H&H soon as an elk slayer so I am saving them for that project. It's almost enough excitement for me to safe queen my 6mms and 6.5mms and go back to .30 cals...
Those Grand Slams should work great. I used them in my 7mm RM for 20+ years. Didn't recover one until the last year as they kept punching through. The one I recovered destroyed both shoulder joints of a 5x5 bull and still retained over 70% of its original weight. My hunting buddy still uses them in his 7mm RM, no complaints.
Good luck on your H&H conversion.
