Hmm, how irresponsible of me! I totally posted this thread and forgot to come back to check on it…
For the confused:
Issue #94 of Dragon came out in 1986 – this was well into first edition, and only a few years before second edition came out. So, no specific critical hit system, but I’m sure there was some sort of “called shot” system in place, as you see creatures with 2 or more AC’s from time to time (one would be if you hit the head, another might be if you hit the tail, or the arm, or whatever). Of course, this system was eliminated for 3E.
Also, another thing to keep in mind: while 1E had age categories for dragons, there were only 10 IIRC and did not yet go as high as “great wyrm”. Thus, when Roger Moore created this creature we are converting (we have renamed it to “great elder wyrm” to avoid that sort of confusion) there was no current specific definition of the term “great wyrm”, and it is therefore a completely separate creature from what we now know today as “great wyrm” dragons.
I still think we have room to include interesting “critical hits” such as this, and some of you have some pretty good ideas. We would need to, I think, remove the percentage chance of getting a crit, as there are now very few % rolls compared to the way it was in 1E/2E.