[Koha] regex to put space between the classification number and author letters

Hi everyone, I have about 5000 records with no space between the classification number and author letters. Here are a few examples: 491.431SA 431PA 260RE I would like to add a space so that they become: 491.431 SA 431 PA 260 RE Is there a way to add the space in the call number using the Koha item batch modification? I feel like I could use regex to add a space after the numbers or before the letters but don't know enough about regex to know how. Could someone help? Or offer another way to edit them? Thanks, Lauren