I'd be interested in that, depending on how it is treated. Quite a while ago, I came up with such a setting for the Vampire game system (of all systems!), and although it worked well, I think it could be better suited to a system like RuneQuest's, what with the hit locations and the emphasis on improving personal excellence in specific areas. If done right.
For such a setting, I'd personally like to see some deep (not necessarily realistic) treatment of the various styles of martial arts, a'la the old "Kung Fu Theater" shows I'd see dubbed into English on Saturday afternoon television. For that to work well, I believe you'd have to come up with a richer replacement for the "Martial Arts" skill, though.
A generic "Martial Arts" skill mechanic is fine in a setting where people with martial arts knowledge are rare, but if you want to focus on a variety of styles and tecniques and their interplay ("Drunken Monkey is the only style that can beat Eagle's Claw!"), it could really add to the gameplay experience to flesh out a game mechanic that celebrates those unique story hooks you only find in flicks like Crouching Tiger, Hidden Dragon.
I'm thinking that it would be closer to a magic system than the raw combat rules, with % rolls in schools and techniques and special moves that burn MP, for instance, but perhaps someone has a more clever idea.
Luckily, there are plenty of hooks in the RuneQuest system that you can hang mechanics like these off of if you design carefully. If you want help fleshing something like this out, let me know, and depending on how well what you're envisioning meshes with what I'm envisioning, I could probably contribute some content and/or design.