We have put together two 8 twist .270 Shermans, one is a 25" and the other is a suppressed 19", they work pretty well, and we have taken a couple elk with them. We have used the 170 Berger EOL, the 140 Badlands Super Bulldozer, and the 126 Cayuga. The 140 SBD is quite impressive ballistically with a .333 G7 bc and the speeds you can get the 140 scootin, it actually outperforms the Berger 170 in external ballistics (less drop, less wind, the same or more energy at range, and more retained velocity). We also used it to kill an elk, a deer, and several pronghorn very well this year. In the 19" barrel, we were running it at a mild 3030 fps, in a standard .270 with a 24" or so, you should be able to get a fair bit more than that, and I wouldn't hesitate to use it on elk out to 750 at those speeds.
If you want to run the 156 Hammer, talk to Steve, it may be worth it to go with a 7.5 twist to ensure stability, especially if you go with a button rifled barrel. It isn't uncommon for button rifled barrels to be off on their twist by half an inch at times, sometimes more. Also a 7.5 twist shouldn't negatively impact the use of a 150 ABLR, or you could run the 165 ABLR without a second thought.