The powder that yields the highest velocity out of a long barrel generally will yield the highest velocity out of a short barrel.
2740 seems a bit high based on what QL is saying here, but there are variables that could make that velocity possible...and maybe even safe.
QL is not perfect, but it usually provides a pretty reliable picture. If I wanted to get the highest velocity out of the 7-08 with a 140, I'd probably go with H4895, but that's because of certain things I look for when choosing a powder. I don't think there's any doubt whatsoever that higher velocities can be achieved with powders other than Benchmark. Accuracy is much more difficult to predict than velocity, though.
God I am hating caliber threads more and more