Hi 375er,
I have not used the 300 gr CEB, but have used the 235 gr Safari Raptor in 375. Absolutely flattens good sized cow elk. Have also used the 370 gr in a 450/400 NE for American bison and cape buffalo, and also a 275 Rigby with 130 gr Safari Raptor. Any CEB in the 375 will work great for you. I use CEB bullets for all my hunting these days.