Install a small alternator from a foreign car.----Make brackets and adapters.----Modify cowling as needed .----Might need to add a " performance " bulge so cowling fits
People often run motors till they go boom.-----The lessons are only taken to heart after the wallet is empty.----And what is the model # of this --" Johnson " ---outboard.-----Johnson is easy to repair.---Other brands may not be.
I started working on outboards in 1968.---Some issues are easy to solve on older motors.----Do yourself a favor and do a compression test on this motor.---Keep the actual values for future reference and post them here.