If you're using the same coil you had with the point-type ignition, either run the original gap, or increase it a little. Most coils for point ignition systems top out at about 25,000 volts, regardless of how they're triggered, with points or electronically. With a good clean set of plugs, the firing voltage will be about 8,000 volts, increasing to 12,000 or so under load. If you increase the gap too much without going to a high-output coil, the engine will miss on acceleration.
Jerry