@mixin inline-block-lr($container,$left,$right){
    #{$container}{
        text-align: justify;

        &:after{
            content: '';
            display: inline-block;
            width: 100%;
            height: 0;
            font-size:0;
            line-height:0;
        }
    }

    #{$left} {
        display: inline-block;
        vertical-align: middle;
    }

    #{$right} {
        display: inline-block;
        vertical-align: middle;
    }
}
It accepts 3 parameters. The container, the left and the right element. For example, to fit the question, you could use it like this:

@include inline-block-lr('header', 'h1', 'nav');