for an outline of a TIFF -> PDF Acrobat X Pro Action. Something similar can be done with an Acrobat Pro 8/9 Batch Sequence.
You can process the JPEGs to PDF and OCR then use Acrobat's Combine feature.
Or combine then OCR.
300 ppi images of textual content is pretty much the "sweet spot" for Acrobat's OCR.
If the JPEG files are too much lower you'll not get very useful OCR output.
Saying thte same thing in a slightly different manner. You can select the JPegs and drag them to an Acrobat window or open the first desired JPeg and then use the Document>Insert Pages to add the rest. I would then recommend using the pages list to reorder the pages if required. Upon completion, I would save and then on a copy run OCR. With the OCR, select the searchable format, not clearscan for what you have indicated are your needs. Save the result.
As already mentioned, 300dpi resolution is typically needed for a good quality result.