Here is static timing for points on a '70 and up Shovel in a nutshell:
First, set you point gap to .018". Check it on both point cam lobes...the closer you can get it to equal the better, but the factory spec is within .004 of each other (but you can get it within .001" if you take the time to fully center the advance assembly on the end of the cam).
Once the point gap is correct, bring the FRONT cylinder up on it's compression stroke...if you aren't sure, you can be sure by collapsing the front intake valve pushrod cover and watching the lifter...as you're pushing the engine through, that lifter will come up as the intake valve is opening...then it will go down as the valve is closing...when it's down, your front cylinder is coming up on it's compression stroke. Stop there!
Look in the timing hole on the primary side of the bike (remove the plug first!)....VERY slowly, bump the engine over a bit with the kicker (or put the rear wheel off the ground and with the bike in high gear use the wheel to move the engine)...you are looking for the TDC mark on your flywheels (stock flywheels up through early 1980 have a small drilled dot low in the timing hole for the TDC mark and a vertical line for the advance mark....after early 1980 the factory changed the TDC mark to the vertical line...how's that for STUPID...also, the early flywheels have another larger drilled dot up higher in the hole...that's the REAR cylinder advance mark...don't confuse it with the small, low dot)...when you do find the TDC mark, position it so it's JUST inside of the timing hole...you want the back edge of the TDC mark touching the back edge of the timing hole, understand?
OK, no go back around to the points. Connect a 12 volt DC volt meter with the negative lead to a good ground and the positive lead to the wiring terminal on the points....or use a simple test lamp wired up between a ground and the points. Turn on your ignition switch. When the points are OPEN, the meter will register 12 volts or the test lamp will light. When the points are closed, your meter will zero out or the lamp will go off.
You want to set the points plate so the points are JUST BARELY beginning to open at the leading edge of the narrow lobe on your points cam. Turning the plate counterclockwise retards the timing, turning it clockwise advances it. As a starting point, loosen the ignition plate screws and turn the plate ALL the way counterclockwise so it's fully retarded and the points are closed (no voltage at meter or test lamp is off)...slowly turn it back clockwise until the very instant the meter shows battery voltage or the test lamp lights...STOP!! You want the points to BARELY be opening...so little that you almost can't "see" it...but you'll know they're open because of the meter or test lamp energizing. Lock the plate down. If you get it just right, you'll be able to just touch the top point with your fingertip and make the meter or light go off, then come back on as soon as you remove your finger.
Verify that the flywheels didn't shift, the TDC mark is still in the leading edge of the timing hole...all set. Put the timing plug back in, put the point cover back on...have fun.
Good procedure and explanation by 77. The only thing I do different is to place a radio set on the AM band near the bike. Set the dial between stations so you hear static. With the ignition on, the radio will "POP' when the points break. This is a little bit easier than watching for the light or meter to register.