Unfortunately, the most ludicrous solution to your problem that I can think of on short notice involves extracting the letterhead to an image and then inserting it into the background of the PostScript document whose troff source has left space for it.
I'm sure that if you give me a few hours, I can also work in an IBM 370 emulated on a Raspberry Pi and a Lego Mindstorms robot.
Follow friends and discover new ones. Publish anything you want: links, pictures, text, video. This server is run by the main developers of the Mastodon project. Everyone is welcome as long as you follow our code of conduct!