Converting a left side vent is pretty much out of the question, among other things the vanes point in the wrong direction.
While its cool to save weight, if your windows fog up any time while cruising it will stop you dead in your tracks with no fan from the heater box. You can do without the heat but you really need that air movement. I personnal didn't think the hassle (one time) was worth the slight weight savings !! That's why I sold that box !!