I'm picking up a set of KWv3's, and the previous owner isn't sure what springs are included. The setup is brand new, and has never been installed, so I'd assume the spring rates are typical, but is there a way to tell?

 

yes - see what's written on the spring.
80-140 or something like this IIRC means 8.3 kg/m.
Google it and you'll find right on.

 

the 80n/mm springs are the 457 lb/in and the 90 is the 515 lb/in

 

The springs are labeled with part numbers. Get the numbers off the springs and then go to the KW website and look it up in their catalog.