Your kidding right ? You dont have any traction helpers at all ,just stock springs and its planting the tires enough to run those #'s ? What are your 60' times ?
That would be my buddy Tim in his all steel '69 Dart with a Indy headed 500 roller motor. The car is currently here and for sale. He also ran low 10's with a S/B stroker in the same year car, not the exact car for sale now.
His rear end suspention in the S/B Dart was in fact stock 6cyl. springs and a 8-3/4. I do beileve the current big block car is also a 6cyl spring set up. Completely OE for the year. No pinion snubber ethier IIRC. I'll have to (re) ask him.
He ran very wide tires. 60 ft. times with the S/B were 2.0's - 1.9's, the BB is IIRC 1.6 or 1.5's pullin the wheels.