Yeah 302's are junk. Car still managed a 12.6 @ 107 with 1 dead cylinder another with heavy scoring and an electric fuel pump that was disconnecting during the run and ran lean at mid to top end of the track. Add to that a lowly performer manifold and a 600 edelbrock with a 222/234 hydraulic cam. Did I mention it only has about a 140 cc intake port volume.......
Again saw a 318 with ported 318 heads stock valves run 12.7's in a stock sedan that had to be at 3400 without driver.
Airflow is is one thing using it is another. When all else fails put bigger heads on it and spin it higher because you cant extract the efficiency at lower rpms to get the car to make the power you need.