The 3.4l have much better torque. The single number for the maximal torque is misleading. Better to compare the whole torque curves:
As you can see, the 3.4l engine have an amazingly flat curve. It provides the level 200 lb-ft torque from 1800 rpm to 3500 rpm, with only slightly more between 3500 and 4500. In other words, provides more torque just above idle, at 1800, than 3.1l engine provides working hard at 3500-4000.
By the way, GA cruises at the 1800 rpm at the highway speed, 60-70 mph.