I have been shooting the broach-cut Oly, 1:10 twist barrel for over 15 years. I shoot mostly 50 grain bullets with it but have tested it with bullets up to the 68 grain heavy match bullets from Black Hills. Any of the 1:10's that I have tried that load on have shot well. I also happen to have a 1:14 twist, broach-cut barrel. That does a great job as far as stability and accuracy with the Sierra 55 grain spitzer. I really loves the thin-skinned 45 and 50 grain bullets though. I have heard it said many times for people to get the 1:8 because you can still shoot the lighter bullets. Well, this is true, but only to a certain extent. My 1:14, and any of the others that I have built on that twist, shoot the light bullets better than my 1:10 and especially the 1:8. Yes, I have shot groups with 1:8 twist uppers and 50 grain bullets that most would say were good groups. But over hundreds of barrels you get to see more of the picture, and the slower twist does a better job of fine accuracy with light bullets.
As you hear all the time "your mileage may vary". That statement says allot. Just the other day there was a thread where someone was talking about 30 grain, .17 caliber Berger bullets. I made the statement that I had tried many times to shoot that bullet in a 1:10 twist barrel and all I ever got was key-holes. I talked to Walt Berger and he told me I needed a 9 twist. I switched to a 9 twist and they shot great. 2 minuets later, one of our members spoke up and said that he routinely shoots 30 grain Bergers from his 1:10 with good results, and I don't doubt him!
The gentleman that posted the question has one of my barrels. I'm certain it will do a good job on bullets to the mid 60 grain area, but I don't have enough experience with bullet selection for predator hunting to help him beyond that.