Search an expression (code) and turn the whole line into heading

[SuperDocT]

Hi, I look for the correct Macro Code in order to search into the whole document for a certain code and turn the whole line into heading 6
I precise that the line containing the code can be in any format (heading/normal etc...)
This is the code I wrote and obviously doesn't work:

Sub head6_to_heading()
Dim doc As Word.Document
    Dim rng As Word.Range
    Set doc = ActiveDocument
    Set rng = doc.Content
    With rng.Find
    .Text = "(head-"
    .MatchCase = False
    .MatchWholeWord = False
    .Replacement.Style = doc.Styles("Heading 6").ParagraphFormat
    .Wrap = wdFindStop
    End With
End Sub

Thanks by advance