Thanks for the replies @sylumer and @drdrang! I was table to take a little of your overlay script and also a prebuilt script PDFpen has to solve the stamping portion. I just haven’t yet had a chance to pass the text to it and get it all working together.
This was one of those things where the automated/quick solution was taking way longer than just muscling through it and I was running out of time. So now I’ve got a month to work through the automation before the next batch!
Thanks for pointing me in the right direction.