You’d better use a desktop PDF to Word converter then, since online ones basically have a limited file size. For Windows users, Readiris 16 is recommended, it can convert any PDFs to Word, including paper files, scanned PDF and native PDF to editable Word, or other formats. It provides highly accurate conversion results. For Mac users, PDF Converter OCR is a good choice, it allows users to convert any PDFs and images to searchable PDF, editable Word, and other 14 formats. Also, it supports to create PDF from Word, or other documents with one click.
You need to install and install Adobe Reader (it's free). When converting, convert it to PDF to convert image to PDF, and you can't just turn them into OCR. Make sure that you need to use appropriate conversion tools. For conversion, it's more important to ensure accurate results. If you are not too confident in manual conversion process, it's possible that you can always convert it to OCR using the free software PDF to OCR and OCR Tools from OCR Converter.com. It's a free to use software with automatic conversion capabilities, allowing conversion of a PDF to OCR in seconds.