Here are the only 1970's DC stories by Kirby not reprinted recently in collected hardcover or trade form, JUSTICE INC. 2-4 by Kirby. Issue 1 by Al McWilliams is also linked at the end after the Kirby stories. All written by Dennis O'Neil, the only O'Neil/Kirby series collaboration. (With the exception of RICHARD DRAGON KUNG FU FIGHTER 3, Sept 1975.)
Another crimefighting pulp adventure character, JUSTICE INC is an interesting companion series to O'Neil's run on THE SHADOW during the same period.

DC even did a new series starring the Avenger character (art by Scott Hampton, as a backup series in the 2010 DOC SAVAGE series) in the last few years, so clearly DC has the rights to publish these stories, but for some reason just didn't include it in the KIRBY OMNIBUS 2 volume!