is there a practical and durable way of building up the key on the crank sprocket which locks the harmonic balancer to it once the crank bolt is torqued down to specs?

the key on the crank sprocket is partially eroded with only one side still at full height. i would say 3/4's of the key is worn. this came off a parts car with intact cam and intermediate sprockets. only the crank sprocket was damaged. the balancer will sit with a firm set once its on. nevertheless amount of the key left gives a hanging by a thread feeling to me.

any ideas to build it up or some other method of making a more definitive lock