LASD CCW Modifications Question

So, I am looking to get fill up my 3rd slot for CCW and see a good deal on a Glock 22 gen 3 (.40 cal). I already have a Glock 17 gen 3 (9mm) complete slide that I have been sitting on and was wondering how it would go onto my CCW when I qualify.

Through LASD - https://lasd.org/ccw/

I see that it says "In addition, the caliber of the firearms must all match on all paperwork (AFS, DROS, Shooting Proficiency Standards form and Certificate of Completion and DOJ)."

So seems like I have to qualify with it in 40 cal, but after would I be able to change it to the 17 slide?

I am going to ask the IA but was just first wondering if any of you knew.