Cylinder head discussion 340 with stock above deck pistons

So my ‘64 Dart had a ‘71 360 with stock small valve ‘587 heads, H116CP pistons (9.2:1cr actual), a CompCams 268AH10 cam, Eddy LD340 intake, StreetDemon 750, exhaust manifolds, close ratio 4spd and a 3.55fd rear gear, and it ran a 13.50et.

Your setup should run better than 13.8s off the bottle. Is the car overly heavy? What is the actual car? And what’s your 60ft, 1/8th mile et and mph, compared to the 1/4 et and mph of the same run?