Question about voltage ratings on constant current LED Drivers
The LED itself will limit the voltage when the 1.4A flows through it. That voltage will be somewhere between 28V and 32V. 

It is only important that the possible range of LED array forward voltages (as measured at the operating current) is contained entirely within the range of permissible output voltages of the driver. 

Of course you will need an adequate heat sink for the 40W or so maximum power that the array will have to dissipate.