Guesswork, I grant you.
I bought a KLR-specific Olympia sprocket-and-chain set.
I figured, if the sprocket has a BOSS, it's there for a purpose.
Thus, I put the boss, the thicker part of the sprocket, against the engine side of the countershaft.
The EFFECT of this installation configuration remains: Moves the sprocket teeth OUTBOARD of the engine, in contrast to inboard, as would the reverse installation.
Have I done wrong, pdwestman?
The confiruation has lasted a number of thousands of miles, so far, without obvious damage or compromise; I'll be CRUSHED if I've been living in error this long!
(I hope the word picture above of the installation configuration is clear; my, a picture or accurate sketch would be so USEFUL at times like this!)