you don't need an O2 sensor to tune a street car. A holley will require tuning as well. Both carbs have +'s and -'s. The holeey once tuned will give you much better throttle response. Easy way to tell is to buy a used Holley a 650DP should work fine. Order a rebuild kit, once inside install 28 squirters, a 6.5PV (should work w/ your cam) and start w/ 72 front 78 rear jets. Bolt it up and do you vacuum test to set the idle speeds and mixtures.