MS-1 with the 'extra' code loaded could do his ignition-only system as well.

FWIW, lean burn WAS ignition-only. The lean burn carbs were not computer controlled, they were simply smogger era emissions jetted thermoquads. After lean burn went the way of the dinosaur, we got the electronic feedback carbs. On those ones the computer modules also did spark and the computer units themselves were a lot more reliable than the old lean burn computers.