Rebrand 10,000 PDF files

Seeking someone capable of writing a script (or combination of scripts) capable of taking in a very large number of PDF documents with one of a small number of appearances, and replacing logo and cover images with new material in the same location. Roughly half of the files will be in the "modern" format, as PDFs with isolated text and images. The other half will be in the "historical" format, which are little more than scanned PDFs. Their covers will have to be entirely replaced with a new, more modern cover - except that they must keep the name and designation from the original. Some manual input (identifying which type of file it is, rekeying the title) is assumed to be required, but the less the better. The goal is to produce a solution that is less time intensive than a full manual reprocessing.