FEENIX has the best recommendations I would say.
Regarding another bolt to get bigger cartridge, there is no need. My Rem 721 bolt was opened for the 270 Allen Magnum cartridge without any problems. The problem was after shooting out 2 barrels in less than 1600 rounds the problem was now I needed a new bolt to get a more sane cartridge.
The 270 Win with a 27" barrel gets enough velocity with 150 Bergers to qualify as an elk rifle to nearly your suggested distance. Just "nearly" for my tastes though.
Idaho CTD's threads on the 270 Sherman and 270 SS should give you all the info needed to make a darn good choice to meet your needs.
My experience with the 270 AM and studies of the elkaholics Sherman offerings I'm strongly suggesting a Sherman offering would be very strong competitor to the Allen Mag in 270 for anything you'd want to do with it.
The 165 Matrix @ at around 3100 MV out of a 24" barrel would be very hard to pass on. (At least for us velocity hawgs)
Oh, and pushing a 140 class offering at 3200 out of a Winny is pretty much a piece of cake, with the right barrel.