My 69 RR, with a .060 over 383, pistons .065 in the hole, ran 13.08 at 105 mph................

it had bowl ported 516's with the 1.74 exhaust valve added.

NOT bad since it had a terrible 1.99 60' time. More hook/bite (better burnout) and with that mph 12's are not a problem.

The shortblock had unknown mileage since it came in the car with no known history. Pistons rocked in the bores at TDC.

The car weighed 3610 lbs with me in it.

Yep, 516's are a boat anchor/doorstop, BUT for an econo mild to warm application (especially a 383) they have their purpose.