02s are extremely accurate at 14.7-1 or stoichic. Because a/f ratio must remain 14.7 -1 plus or minus 2% for efficient catalyst operation, this is where 02sensors are designed to work. 14.7-1 equals 450 millivolts of 02 voltage. At 12-1 a/f your 02 will read 800 millivolts. You can buy a wide band 02 for around $500 from TPIS or Accel I think. Don't misunderstand me this is a good tuning tool to use for your car but will only be very accurate at 14.7-1. Max power air to fuel ratio is about 12-1. Unfortunately this is very dirty for the environment as lots of unburned hrdrocarbons and carbon monoxide escape into the air. But if you tune for 14.7-1 with your old 144 it'd be too lean and probobly burn a valve or piston. Good luck