If your brewhouse is between 3 and 10 BBLs, I'm guessing you won't have rakes in the mash tun and will need to agitate the mash by hand. If this is the case, I think you can assume that your efficiency won't be much different than your homebrewing efficiency (at least, it's a good place to start, like others have suggested). But as you start to get into brewhouse sizes like 15, 20, 30 BBLS, I think the efficiency should increase pretty dramatically, as the mash is constantly agitated by rakes in those systems (more like 80%-85%). At least, this is what my research over the past few months leads me to believe.