I had to read back a bit to see what you ended up with for a combo.
You are obviously experiencing some "new combo blues". One you get it sorted out it should go(at least) 8-10mph better. ET's are much more dependant on how well you can get the car to leave. "Street" cars with a std trans and mild gearing don't usually 60' nearly as well as a comparable auto, but mid-low 12's should be no problem.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads