The only handicap of the .270 would be bullet options for shooting distance. Well beyond 500 yards. Not much in weight class for Elk at any significant range. Berger's 170 would work assuming it will shoot well in a particular rifle. If not, your out of heavy bullet options. The 280AI has options from 160-195s for Elk or any large animals. I'd say that would justify use for a 280AI. Anything up to 500 yards, the 270 would handle with the 150 class boat tail hunting bullets. Even the Nosler partition works at 400-500 yardsI am all for building rifles. Hell I get halfway through with one and I am already working in the next one. But given what you have I don’t see what a 280 ai as a huge step up over a 270. A well loaded 270 win is a heck of a caliber.