I am doing exactly this at the moment. I own 2, 260's and love the cartridge, but in my opinion, elk at range is far beyond the reasonable expectations of its capabilities. The 7mm-08 and 308 are better, but still not bringing enough to the table. A 7mm or 30 cal magnum are more sensible options. None of this is meant to say that elk cant be killed with the 243,7-08, or the 308, they just dont leave much margin for error.
Given the expense and time that I will have invested in a guided wilderness elk hunt, I am not willing to take a chance with marginal ballistics. I have waited, planned, and saved for this hunt for a long time. Nothing will be left to chance. Mine is a Winchester M-70 in 300 WSM in a Manners stock. Still havent decided on a final load but it will likely be a 180 gr Barnes TSX-BT bullet if I can devolop a load that my rifle likes. If that doesnt work, I will replace the factory tube with a match grade barrel.