I switched over to the Drupal CMS. I briefly thought about using Gallery with Drupal but I thought it would be overkill. After a brief search I found Drupal School also has a video demonstrating how to implement the handbook example Drupal School: 009 Maintainable Gallery. I followed along with the video and also read the handbook entry HowTo: Create an image gallery using only CCK and Views. A few customizations later, I had something ready to replace the old site.
I was never very satisfied with the architecture of the site because the gallery script that I was using (4images) looked very different. I did eventually create a theme for the gallery that made it visually similar but I still was not satisfied. Moving everything into a CMS makes things simpler.