I have Spartan #9. I bought a copy from Noble Knight last year for $50; it's one of the more expensive collectibles I've bought. I was interested in seeing it b/c J. Eric Holmes mentions in his
FRP book that he used the combat system from it when he started playing, because the OD&D combat system was confusing. (The irony here is that I find the Warlock combat system to be overly complicated; it actually says "the numbers involved in our combat system may look a bit frightening").
The Warlock article takes up most of Spartan #9 (pages 4-37 of 50 pages). It's not an article about the creation of the Warlock rules - it's the rules themselves - an earlier version of the same material found in the Complete Warlock. (For comparison, I also have a beat-up copy of the CW I picked up on the cheap in a lot, thanks to lokiwookie here). There is a brief introduction, three paragraphs, that describes the development of the system, but it's found in almost identical form in the CW.
The Spartan Warlock rules are a very early (Aug 1975!) clarification & expansion of Vol I of OD&D - Men & Magic plus the M&M additions from Greyhawk, though there's a lot of (
IMO) unneccesary complexity added to the rules, which gets worse in the CW (for example, a quadruple magical-fighting-cleric-thief class). Echoing the change in OD&D, the Spartan Warlock rules refer to hobbits whereas the CW refers to halflings.
By the way the picture shown for the "draft" copy on afterglow2 looks identical to the first page of the magazine article. It's also the same length (34 pages). Is it possible this draft is just a photocopy or cut-out of the article?