Messing with my shifter today -- I have no reference marks for the orientation of the arm on the shaft. What position (like, in terms of arms on a clock) should I keep the notch?  The way I have it on right now is just God awful, of course I'm out without a wrench.... Foolish.

Look at the relative positions of shafts and levers.  The maximum leverage happens when things are at right angles.  Also, with something like a shift lever, it will have equal motion in both directions so you'll want to position the lever in the "equilibrium" or mid-position so that you get equal motion in both directions when it is actuated.  Think about how bad it might be if you had the lever clocked 2-4 notches to one side.  That might make it almost impossible to move it farther in that direction.

So with the shifter that moves in both directions I'd try to have the connecting rod attach at a right angle to the shifter when it is in the "at rest" position.

However, for a drum brake lever, you want the cable/rod and lever to make a right angle to each other at the point where you are trying to apply maximum force (ie. the shoes are hard against the drum).  That gives you the most leverage on the brake shoes.

Good points, Micheal.  Mine goes up and down good and the rod doesn't hit anything.  It works.  Good enough.  LOL.