I am in full belief that there is a big difference between short fat bullets and longer ones of the same caliber or long bullets in smaller calibers of equal weight. But when you mentioned you wanted to take elk as far as your 300 WSM
was capable, you are describing a high BC heavy for caliber bullet.
These are just my personal opinions my friend. Not saying the 155's would not kill elk, we all know they would. But just not a good choice in my book for a 300 elk rifle. We have had enough threads with disappointed shooters because they used a small for cal bullet to hunt large game.
But in the end it is your choice.