You dont mention whether the engine is mechanical advance or Synchro spark but it can be replaced with an Rcexl ignition in either case , just a little more work if it is mechanical advance.
The Rcexl and the C&H are very similar if not identical internally although the pick up sensors may use different connectors and mounting methods. There are several vendors for Rcexl or Rcxp that can help you out with a kit that will fit the Brison