First off all great choice with AutomationDirect. I use there products constantly and never had any issues.
Okay the drive is 115V power in and it produces 3phase out. You need to use a 1HP 3phase motor. AutomationDirect sells real nice 3phase 56C motors that are very reasonably priced.
1725RPM is a 4pole motor
3400RPM is a 2pole motor
Both have pros and cons but for your situation with needing higher speed. Go with the 2pole motor. You can over speed motors. This means running the frequency higher then the name plate rating which is 60Hz. It's not always a good idea to over speed the motor because it can be dangerous. There are inverter duty motors that are capable of handling higher frequencies.
It's better to get the higher speed with pulleys rather then over speeding the motor.