Hi Roger,
Good question! I scrape the lock mortice to smooth the bottoms of the inlets and I clean the edges of the inlets so they are smooth. I am not anal, however, about surgically removing just enough wood to fit the lock parts. All of my mortices have more wood removed than absolutely necessary. For example, rarely do any of my inlets clearly show the outline of the bridle. I would rather do that than fuss too much inletting individual parts and risk damaging the edge of the mortice with a scraper or chisel. I clean the edges so that there is no chance that the lockplate or any internal part can grab a splinter of wood and tear it out when the lock is removed for cleaning. Because I live in a very, very wet climate, I seal the lock mortice with whatever finish I am using on the stock (usually some combination that includes polyurethane and tung oil).
dave