I just finished the project and the Script made it happen. I was able to run several trials, creating wide masks and dividing them into portrait segments. I finally landed on 7, that got all the images onto the page in neat rows. Loading the images was so easy and I was able to adjust each on to the drop shadow was visible, then center them inside the mask.
I can't thank you enough for the gem! I have several more collections my client wants me to put onto posters and this is going to make the job so easy!