6700 rpm's is a late shift for STOCK at WOT it should complete the shift at 6000 (+/- 200) rpm so unless your tranny is shifting extremely slow (flaring) 6700 is WAY late.
If JMOD tranny, and stock PCM, it should complete the shift at 6000
Although I've heard that the factory tach can be "off" in the upper rpm range as well.
LSC? 3.27's? I missed that part....stock base gears, 6000 rpm shift = trapping at 5850 rpms (approx) in 2nd gear and shifting in to 3rd just past the stripe.
I too thought your 60's were great for a stocker on street tires.
The "art of the launch" is key in these cars
also, staging as shallow as you can = poor 60 foot, but a lower ET
creep in as far as you dare on the second bulb = lower 60 ft, but slower ET.