Grey Seen as Leading Paramount Candidate  NEW YORK (Reuters) - Brad Grey, executive producer of the  hit television show "The Sopranos" and chairman of a top  Hollywood talent management firm, has emerged as the leading  candidate to succeed Sherry Lansing as head of Viacom Inc.'s  &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=VIAb.N target=/stocks/quickinfo/fullquote"&gt;VIAb.N&lt;/A&gt; Paramount Pictures, the Wall Street Journal reported  on Sunday.