I wrote an extensive article for SUPERFORD magazine in 1986 (the August issue as I recall).There are no performance books on the topic, but www.fordsix.com has a whole forum devoted to the 240 / 300 sixes. Also the 12 PORT NEWS has member written articles. What are you building?
Good luck.

FORD 300 inline six - THE BEST KEPT SECRET IN DRAG RACING!