I'd compare the bullets I want to use in each and then go from there. The figure out what flings them the best.
I've never hunted sheep but it's something I'd love to do and as such I've done the whole "design your sheep rifle in your head" exercise (mostly while stuck in meetings at work) and usually came up with a Montana in 260 or 6.5 Creedmoor, topped with a good scope. That's assuming the internet's right about needing something lightweight to schlep up one mountain and down the other.
