There is a problem in using a KB3 program in a SETUP. KB3 mode completely changes the way the K2500 creates sound. To create a KB3 program, most of the available resources (polyphony) are taken to create the organ model.(posted 9251 days ago)Using any organ sound that is non-KB3 would allow you to create the setup that you are asking and much more.
Since you asked about KDFX as well I should tell you that all the regular sampled organs are re-done when KDFX is installed. Not only do you get chorus/vibrato and a great leslie, they've also added some EQ control helps simulate some drawbar control.
You may also want to download the K2000-B3 sounds that Dan Fisher did. They are on the SweetwaterSound Website. They're quite good and give you lots of control without using all of the horsepower of KB3 mode.