Installed this setup on my 79 SC. Its now more responsive and sound great.
Went for the 2-1 70mm Dansk sport muffler. Its not too loud but has a nice scream >4000rpm. The loose 84mm 2-1 drone to much at cruising speed and the 84mm 2-2 is worse. Remember to change the oil lines and be careful at the thermostat - the threads often come off with the steel nut. There is a fix kit available using a longer nut that can catch the remaining threads if this happens. The SSI's are now also made by Dansk and mine needed a little adjustment to fit under the chain houses. (hammer)
This may not be necessary on a 82 since there is more clearance using the thick flange type I think you would need for 80-83 SC. The Dansk factory (JP Group) is only one hour away from me, so I did complain - they appriciated the feedback and hopefully quality has improved.