I've never hunted elk, but I understand the 35 Whelen or Improved would be sufficent.
I just completed a Turk Mauser conversion into 35 Whelen, and it all worked pretty slick. I did 90% of it myself (everything except chambering and bluing), dropped it in a Boyds Laminate stock this weekend, and will have a scope on it by this weekend.
In the big picture, you can buy a factory gun for just about as cheap, but theres something about using a gun you put together yourself......
35 Whelen or Improved version gets my vote.
Erik
Rusty Axe Camp