A late update: finally finished off M.E.'s Best O' the West with #9. Now if I could only get the Ghost Rider origin story (Tim Holt 11 or the IW reprint) and an original Redmask 47, not to mention the rest of the GR issues.
And, my penultimate Air Fighters fiche-replacement scan: #3 with the origin of The Heap!
Still to come: #7. I doubt I'll ever find a cheap-enough copy of #2 (which has the first appearances of Airboy, Black Angel, Iron Ace, etc).