Budlight said it well! A lot depends on you and how you are with killing elk. I've killed a pile of the buggers and love hunting them more than anything, I'm as comfortable shooting an elk as a lot of guys are shooting a deer. I know very well the limitations of me and my rifle and know what I have to do to effectively kill elk with what I use. I also have no interest in shooting them through the shoulders, loosing even 15lbs of meat is just not acceptable to me and I don't mind shooting one through the lungs and heart and having them go a 20-50yrds and dropping, I have no need to drop them and the way I kill them is fast and clean which allows me a little more range as well. I will say since starting to shoot the 270 WSM I have yet to have an elk take more than a couple steps after taking a Accubond or Berger through the heart/lungs, but I haven't broke 600yrds with it but seeing what it does up to that point I have a lot of confidence well past that. For me I look to stay in the working velocity range and stay at a range I can make a cold bore shot that will not go outside the 10-12 in area I want my bullet to go, some days velocity makes the decision some times conditions, energy wise just for reference I like 1000-1200ft-lbs but I don't put much weight in energy numbers but I do like to see that I'm not plowing dirt. You really seem to be struggling with the idea of killing elk with a 270, the best thing to do is wack one at 300yrds or less with a good shot, it will clear up what it is capable of, the first time I did my jaw dropped as fast as the elk did! For some guys it just won't due for me I'm GTG and have shot the elk to prove it to myself and others I hunt with, but I do it carefully, wounding elk is not acceptable!! I would not shoot an elk very far till any rifle and bullet I shoot are proven with a couple elk under 300yrds, just the way I do it even the 338 RUM and Norma I'm building won't kill a long range elk till they do short range first.
Numbers wise, here's a chart that is what I shoot at the range with the last barrel I wore out, it's actual numbers!! I haven't gotten the new barrels finalized yet so no data yet. Just numbers but with this combo I would do an elk at 800 and if all was right 900ish.
This is a chart for what a 169.5 Wildcat or similar could theoretically do, I'm not running these yet so I'm using number from other guys that have so they are proven but not by myself. This combo I would feel real good to 1000yrds but would look at a 1200yrd shot seriously if conditions were right.