This is precisely what the style library is for. It's a repository for all your styles, and can be set up with multiple different standards. We have three: Inch, dual dimension, and metric. We have two templates, inch and metric. The inch template uses the inch standard by default, but can be switched to dual; the metric template uses the metric standard by default.
Styles and style libraries can be difficult to get your head around, but once you do, they make life so much simpler.