I had a similar problem and ended up using AWS' Textract tool to return the text as well as bounding box data for each letter, then overlayed that on a UI with an SVG of the original page, allowing the user to highlight handwritten and typed text. I plan to open source it so if anyone's interested let me know.
Not a fan of the potential vendor lock in though, so it's only really suitable for those in an already AWS environment not worried about them harvesting your data.