For a variety of reasons I doubt that it would be feasible to think GA could or would contemplate dramatizing the entire run of The Executioner (unless, of course, sales picked up). However, I believe there are a few books in the early series that could be considered as candidates:
Executioner #1 - WAR AGAINST THE MAFIA - The book that started it all. Totally different from the Mack Bolan we are now familiar with, this seminal book deserves to be released by GA as a historical icon. Or at least to show the initial raw characterization in Pendleton's brainchild. Plus, the revenge war on the mafia storyline is different from anything current in the series.
Executioner #38 - SATAN'S SABBATH and/or Executioner #39 - THE NEW WAR - 38 wraps up the basic mafia war (and is the last complete book by Pendleton?) and 39 starts Bolan/John Phoenix on his long journey with and without official sanction.
Additionally, there are various trilogies that cross between the monthly Executioner and bi-monthly Super Bolan books that could be done as a "mini-series" of adventures, such as the Storm Trilogy (Ex 160-161 & SB 27), the Freedom Trilogy (Ex 174-175 & SB 32), the Terror Trilogy (Ex 186-187 & SB 37) and the Medillon Trilogy (Ex 149 & 151 and SB 23).
Just a few thoughts. At a minimun, though, I believe Executioner #1 should be released, just because it's the start of it all and has historical significance. If a decision is ever made to stop releasing the Bolan books, and #1 has not been released, it should be the final release as a farewell gift to the fans.
BTW, thanks again for putting STONY MAN DOCTRINE on the release schedule!