55gn serria SP will do the job nicely it's a favorite in my Moms Mk X. Its taken a dozen or so mulies cleanly,although the operater may have some influence.
Nv allows big game w/"a 22cal or larger center fire w/an oal of 2 inches or greater that produces at least 1000 ft lbs at 100 yds." Which makes a .223 w/55gn SPBT 24"bbl legal ,and rules out a deference loaded 350gn rem RNHP 45-70 from a ported Marlin guide gun.Would a warden give you the long neck if you were hunting elk w/a 223 ? Yes.1 word about elk w/45-70 I doubt it.
Would I take a 223 over even the 22-250 or its Savage parents ? No. Would I hunt elk w/any of the these ? Not on purpose .
Keep it in the vitals,take good shots,use a bullet over 50gn and up,over 50 yds under 225yds and your whitetail will be in a whole lotta trouble.