The Münchener DigilalisierungsZentrum has put what appears to be the complete works of Georg Friedrich Händel on their website:
These editions should be in the public domain in the USA, and the host does not appear to place the same restrictions on use that the Brahms and Mozart collections do. (The Mozart collection features an edition which is not public domain in the US, and both hosts ask users to pledge to limit their use of the archives to fair use.)
The images appear to be in high enough resolution to print legibly, if the 150% button is used.
Frustratingly, it is somewhat tedious to browse, and I don’t see a way to download a work without manually going to each page, and then clicking on the 150% button to get the highest resolution image.
However, IMSLP has been steadily converting the scans to PDF files hosted on their site. Visit the IMSLP page for Handel.