The original LS-37 coil part number is 72-1045 but it seems Johnson recommended the 72-1072 two cylinder coil as a replacement when necessary. Your coil looks to be a two cylinder coil so the two solder tabs on top would be for the spark plug wires and the two leads coming out of it would be for the primary circuit and go to the points and ground. When used in a single cylinder application, one of the spark plug tabs would get wired directly to ground. Using a two cylinder coil in a single cylinder motor should generate a hotter spark as it only has to fire the one plug instead of two at the same time.
As for ignition modules, I have used the red Atom modules meant for outboard magnetos with great success. I’ve also tried the common Nova II modules but found they wouldn’t hold up and burned out in a short time. The Novas were tested in a 70’s two cylinder motor with strong Alnico magnets in the flywheel but they might, and I say might, work better in a pre war motor with iron magnets in the flywheel.
Here the red Atoms are installed in a ’40 Evinrude Zephyr and a ’60 McCulloch 12 horse.
