I put together a search page for the latest files released from the National Archives. The OCR isn't perfect by any means but good enough to find most references. The search results page shows the document title and other metadata and a link to the OCR'ed document. You can search for text in the PDFs with ctrl-f. This only includes the files released on March 18 and March 20, not previous releases.
Note if you put in multiple terms the results will be those documents containing all the terms somewhere in the text.
Have fun!
https://jfkunredacted.com