You can check the spark with the mag cap and cover off. Hold the body of the mag against a bench vice or truck bumper (STEEL!) and the copper coil tab about 3/8"-1/2" away from the vice/bumper. Spin the mag over by hand and see if the sparks. If no spark, back up and recheck the points - gapped to .008"? Visually check the coil for cracks or evidence of arcing. In general, if the coils looks good, it's probably good. The only coils I've ever had to replace had issues you could see. That leaves the condenser - easy to replace if it tests bad.
Once you get spark at the coil tab, then you can assemble the cover and cap. Then place the plugs in their boots and hold them against the mag body. Spin the rotor over by hand and check for spark at the plugs.