Hi Matt,
Three possible leads come to mind.
The National Air Force Museum of Canada (formerly RCAF Museum) in Trenton, Ontario is currently restoring an Anson Mk II.
They have already restored the engines/undercarriage/nacelles so they might have parts left over.
http://airforcemuseum.ca/en/Another possible source is the Reynolds-Alberta Museum in Wetaskiwin, Alberta, as the aforementioned Anson project came from them.
http://machinemuseum.net/The third lead is the Bomber Command Museum of Canada in Nanton, Alberta.
http://www.bombercommandmuseum.ca/Not sure if any of these museums will have spare exhausts, but it's a start.
