Hi, there.
I can only imagine how precious this must be to you! I would be honored to help in any way. So, let me ask some questions to get the conversation going.
Do you need to clean up your typing (typos and misspellings, etc.) from your role in the project? Or are you hoping to clear up aspects of your great-grandfather's story (sometimes in dictation, we garble what we're saying, have to backtrack, etc.)? Or both, maybe? If you and I end up talking, we'll want to clarify this.
It would be perfectly reasonable if you wanted to keep your great-grandfather's gaffes (if any) and only tidy up YOUR fingerprints on the story. I can handle both aspects; I'll just need to know.
The only other point I want to confirm is that this is printed up in some word processor. I once agreed to edit a man's book, and he brought over a couple pounds of paper – yikes! Of course, the online version of that would be screen shots or PDFs. If I was typing everything from scratch from images, I might need to bow out, depending on the length of the story.
Also regarding length, it is terribly difficult to estimate a price or timeframe for the project without an idea how brief or massive the story is. I have estimated 1 day in my bid based on the possibility the story is 40 pages or less. Let's discuss this, too.
Per my skills – my ability to handle your project – I hope my writing here speaks for itself. See my Bio writing on my profile.
I really look forward to reading this tale!
Thank you.