1400 is as high as you need to go.
Keep in mind that torque number is simply getting passed along to other tables as an axis normalizer. If the other tables max out at 1300 or 1400, the ECM will not interpolate any further than those values.
Since the actual outputs (VGT, injection pulsewidth, injection pressure) end normalization at 1400nm, any value 1400nm or higher will drive the ECM to the end of those tables. If those tables end at 1400, then the actual pulsewidth (or other given parameter) will only go to the bottom row/column. Changing it to 1500 or higher will have no actual effect.