I seen a '65 Belvedere run at the local 1/8 mile track. It ran 9.6 with a semi stock 318. It had a performer intake/Edelbrock 600 and dual exhaust. 3 on the tree to. It was an 80's model with swirl port heads. I thought it was respectable.
Years ago, I took my wifes 74 Dart more door to the track The only thing not stock was a aftermarket 4 bbl manifold and a Mopar/Holley carb (the 2 bbl was shot, and I had these parts on the shelf). Single exhaust and 2.9x gears, but a 23 inch slick, leaving in drive. Car ran 15.8's. Engine had over 100,000 miles on it.