Re: 1974 johnson 15 hp
Yes, but do you also want it to charge the battery as that involves a different set of charging coils in the timing plate/ignition. And a new bypass cover (electric starter mount), the starter, starter button and a new flywheel, plus other miscl items.
Go back to the start of this Johnson/Evinrude page & under FAQ, down near the bottom is a link to my articles on 9.9/15hp motors. In this I have one article explaining how to do it.
However on that old a motor, finding the RIGHT parts may be a problem unless you can find a junker/donor motor.