To get it “working” in the most basic sense (that is, gantry moves to verify operation) no, but the short answer is: yes, you’ll need to alter the config file in one way or another after an extensive mechanical change like this.
No config file changes will really be needed if you’re using external stepper drivers and configure them to match the microstepping ratio of the onboard drivers in general, to test the motion. However, with the change to the new gantry you’ll likely need to alter acceleration settings, steps per mm, potentially some endstop settings, and likely a slew of other stuff that goes along with such an extensive motion control change.
We have another forum member who recently performed a similar “conversion” (that turned out to be a full new build in the end). Read through the thread here for an idea of what’s necessary to make that kind of change.