Warren Buffett’s Berkshire Hathaway Inc. said today that it will buy all of the remaining shares in Wesco Financial Corp. that it does not already own in a deal valued at $547.6 million. If Wesco shareholders approve the purchase of roughly 1.4 million shares, which has been approved by the company’s board, they will have a choice of accepting either cash or Class B shares of Berkshire stock in a deal that is expected to close by the end of the second quarter. Wesco is a conglomerate that owns insurance businesses and a mix of operating companies, similar to Berkshire. The Pasadena, Calif., company has been an indirect subsidiary of Berkshire since 1983.