Unless you have the proper tester, going after this ignition system with zero knowledge can be frustrating.
First off....old coils are not deemed good for service by "looking good".
Second, a previous post indicated a cam. He is correct. If you look, you will see that part of the points assembly rides on this cam. On this cam is the word TOP This is important. If you don't see it then pull it off and take a look. Obviously you have to remove the flywheel to look.
When a set of points is at the high side of the cam they will open. It is at this point that you can set the points gap at the proper .020" setting. Set it loose or watch the arm to make sure it is not moving when you slide the feeler gauge in. Only one set will be open at a time. Clean the contact surfaces with emory cloth and de-grease.
On a 1968 engine a field test for coils can be to remove the coil from the block and lay it on paper towels away from the block. Leave your electrical connections intact. Use the paper as an insulator. Spin the engine over and see if your spark comes back. If it does and then goes away again when you re-install the coil you will need a new coil as it is arcing to ground.
You should be able to fire across at least a 1/4" gap. Just grounding the plugs against the block is a cross your fingers and hope for the best kind of test. Up to you what kind of quality workmanship you put into this project.