The simplest method is to use Adobe Acrobat to make a OCR'd PDF. There is no work to that process other than combining all the PDFs you want into a single file

The simplest method is to use Adobe Acrobat to make a OCR'd PDF. There is no work to that process other than combining all the PDFs you want into a single file -- and that's something you can do inside Acrobat, too. It has OCR built in and will save the OCR'd text inside the file. Once you have a PDF, that is an eBook. There are several online converters that can turn it into other formats. As for indices, etc., Acrobat won't make them automatically but your OCR'd eBook is searchable, so it may not matter in the same way it would with print. I'd say the world would be better off with your rough-and-ready PDF (and yes, in the Internet Archive would be great!) than waiting for a perfect hand-made version.