I really like Retumbo in my 270 WSM's down to a 140 gr bullet, usually around 70-71 will be max with the 140, around 68 with the 150. I haven't shot anything other than the 165 or 175 Matrix VLD's since they came out and I run 66gr with the 165 and 64 gr with the 175, I always start with book min loads and work up but this is where I usually end up.
With your twist rate and elevation the 165 Matrix may work, may not, IMO it's worth a try as they are excellent long range hunting bullets, BC running .650 ish I've taken number of elk and deer out past 900 yards easily, they are very impressive on elk!
There are 4 270 cal bullets with a BC .650-.703, all very effective and amazing hammers but unless you have some elevation a 10 twist will be marginal, we have bullets now we need to get manufactures to twist in a 9 twist with the WSM so everyone can benefit!
Just to add, I've shot a lot of 140 Accubonds running them 3350 fps and they will start having opening issues at around 500 yards on deer, I've dug a couple of them out of the ground AFTER going through deer and expansion was getting minimal, elk they open very nice on! The 150 ALR would be very nice BUT again it's needing more twist also!