It can work, but it is obviously not the best choice. You might get a 338 and then you'd have pleanty of reasont to buy several more guns with calibers in between you 243 and your 338...just so you are well served!
But if you are just a little unsure of your 243 and want to keep your choices for a new elk rifle in the "low recoil" area consider a 7 X 57 or a 7mm/08