You won't like this answer, but I'm going to give it anyway.
The best way to convert handwriting into text is to type it up.
Don't skip it just because it's a little tedious. Typing up work is a valuable opportunity for engaging with each word and sentence of the text. Scanning over the text on the screen isn't the same thing. I always use the typing-up of work to do an extra draft (usually I've done a couple of drafts longhand already). Especially since this is an old story - surely in those intervening years you've grown as a writer, or have a different perspective than you had when you wrote it? Isn't this a great chance to revise your work?
Another piece of (probably unwanted) advice. Assuming you don't have a disability that prevents you from touch-typing at speed, you should learn to do so.
Finally, if you do decide to use OCR, you shouldn't rely on its accuracy. Don't trust the damn thing as far as you can throw it. The more accurate it looks, the more likely it is that some subtle error will slip through. Assume it will fill your story with errors.