PDF Letterhead & Image Update

I have an existing PDF that needs a quick but precise refresh. First, every instance of the current letterhead has to be swapped out for the new letterhead artwork I will supply. Alongside that, I need the embedded images adjusted—think size tweaks or clean replacements—so the document’s visual flow matches the updated branding.

Please keep the page layout, margins, and overall formatting identical to the original; the goal is a seamless transition where only the visuals change. Once done, return a high-resolution, print-ready PDF plus an editable file (Illustrator, InDesign, or similar) so I can make future tweaks in-house.