I finally timed the beast.  I bought a piece of plexiglass and used my Harley to power the timing light.  The timing was pretty close after performing the static adjustment.  I had to retard it a little to get the "F" mark lined up with the index on the side case at idle and then the two advance marks straddled the index mark at 4000 rpm so I'm good.  I have a little hesitation at partial throttle opening between 4000 and 6000 rpm so I'm going to be playing witht the carbs the next few days. 

I still have two issues--I need to install the new tube, tire and spokes on the front wheel and figure out why the rear wheel won't spin when torqued to specs. The good news is the 1970 SL100 I bought came with XL250/350 wheels and rims on it so I have a spare rear wheel if I need parts.

Here's the pics of the timing set up, I had to buy another timing light.  I couldn't find mine and then it dawned on me that I'd let a guy at church borrow it, but he moved to Ohio about seven years ago.  I guess I don't use one very often!   The timing light runs off of 12 volts so I had to use another battery. 



The inductive pick up is in the middle of the pic below the gas tank, next to the spark plug boot.



I got an 8X10 piece of plexiglass from Lowe's and cut it down to size and used the engine cover as a template to drill the holes.  I countersunk them so I could use the screws that hold the side cover on.  Its not round, but it does the job.  Oil leaks out of the bottom because there is no gasket to seal it,  but it doesn't take long to time the engine so you don't lose much.



You can see the power cord connected to the Harley here.  You can also use a car.