Since I handload for both my and my dad's 300 Weatherby, I haven't kept up with the factory loads. However, if you're set on a Weatherby, go with the most solid, tough bullet you can get unless you want to recover coyote pieces, instead of coyotes.
a barnes tsx. how does your 300 shoot? for long range it takes a very accurate rifle to hit consistently hit a coyote at "long range". the 300 weatherby I shot did not do that well. also the ammo with barnes bullets is quite pricey. given your rifle and scope were not. trade off of sorts.
Regular old federal premium 180 nosler or sierra will work if you stay off of the shoulder. I have killed several with my 300s and they had baseball size holes. No worse than my 280 with 150s. Head shots will be messy I suspect.