There are a couple of easy checks you might do. Take out the wire for your coil going into the distributor cap. Remove the distributor cap, turn on the key, and use your starter to turn the engine over until the points close. Leave the ignition on. Hold the end of the wire you removed near the engine block while opening the points. You should get a spark to the block from the end of the coil wire. This will ensure the points and coil are getting "juice." Next, have someone turn the engine over and watch for the spark to jump everytime the points open and close. If you have moisture on the wire or it is deteriorated, you might get a little shock surprise, so I recommend holding the wire with a rag or some other insulator.
If you get the spark in the test above, carefully reassemble your distributor cap, making sure the dust cover (if you have one) and the rotor cap are fully down. Sometimes the dust cover does not seat down all the way and this can cause the distributor cap to be too high to make contact with the rotor. If after checking all these things and you do not get a spark, I'd look at replacing the distributor cap.
Here is another "ballpark" setting for the point gap. Use the thickness of a match out of a book of matches to guage the point gap. You can also use two thicknesses of the matchbook cover. This is not scientific, but I've kept old tractors going for years using this method. Good Luck!
