If you are concerned about using test light method, you could use #1 plug wire with spare plug. You should get spark as #1 reaches TDC on firing stroke. That's close enough to start motor. Basically, regardless of points/pertronix, rotor should point to #1 wire on cap with engine at TDC, #1 firing position. Then use timing light.
With test lamp, light should come on as motor passes TDC