Old Starfire
The best person to talk to about this would be Dave Crossno in Oklahoma. He has developed one of the current cases being used in BPCR.
http://www.angelfire.com/ok5/crossnostocks/

The other was Dave Higgenbotham in Texas who is now deceased. The cases are slightly different and one of them should clean up a 40-65 chamber. Some of the good BPCR gunsmith here in the states should have the reamers. If you would rather have it done in Canada, PTG Reamers or Manson reamers should have them.