@Grumbaki - your math is off in your “test run combat”. Descending AC means the orcs chain mail (AC 5) and shield (“+1 AC”) actually means AC 4, not AC 6.
I didn’t look closer to see if that would have affected the “outcome”.
I thank you for looking it over! Never did 2e before so it literally is me working through it in real time. I appreciate pointing out any mistakes I make.
To be honest I played ADnD *at the time* and I *never* did calculations. Even “THACO” confused me. I just stuck to the “To hit” tables - no way to be wrong then.