Corporate Office Properties Trust is closing in on the final stages of the transformation of Arborcrest, its office campus in Blue Bell, Pa. The company began redevelopment of what was the former Unisys Corp. complex in 2008 when it embarked on what will be a $120 million effort to reposition the property once occupied by a single tenant - Unisys - into a series of modern office buildings that would attract top tenants and top rents.