Longer Mont-bell Peak Shell

I have a Mont-bell Peak Shell that I love, except it's too short, my ____ get wet unless I'm wearing rain pants. Does anyone know if they make a longer shell in their Dry-Tec fabric?

Or alternately, would I be screwing up a really nice jacket to add a strip of goretex or something to the bottom? How hard would it be to do nicely?

By the way, I'm only 5' 7''

thanks!