Go with the Lone Wolf barrel, they are the best out there:
This is the model you need:
http://www.lonewolfdist.com/Detail.aspx?PROD=983
Other than that, grab some 9mm Glock 19 magazines and you are good to go.
The only other thing you "could" change is the extractor. The extractor in your gun now is the "striaght" version from the 23 and 32, you could replace it with the "bent" 9mm extractor from the 19... This is only needed if you are getting all your brass thrown straight back in your face when you fire.
I had this barrel for my Glock 23 and periodically had the shells come back and bop me on the head. I didnt mind it much because I wear shooting glasses and a hat when I shoot so it was no concern. Plus I was just lazy because to change the extractor you need to completely strip the lower, and even though Im a Glock Armorer, I just like simply swapping out the barrel and grabbing my 9mm mags when I wanted to change calibers, not have to go through the extractor change everytime. I guess if you planned on changing the 32 to 9mm for an "extended" period of time it might be more worth while.
Hope this helps!