Edited: 8/13/2010 9:11:27 AM by DroptSdime
The Impala bumper was built by Kyle at Guilty by Design.  You could try him. 
http://www.streetsource.com/IM/ViewUser.aspx?IMStyle=&ID=Guiltybydesign Or Mat at McClarys Metalworks.  He's pretty handy with the sheetmetal.
http://www.streetsource.com/im/viewuser.aspx?id=Ice  Or of course Eric at Little Shop of Horrors.