Full weight street car or not, that car should be running mid 10s as it sits. Or atleast running more MPH than it is.
I'd hate to see you tear into the motor and spend money only to find out that it doesn't help your situation. CHIP

5540907-cudadriveway.jpg (31 downloads)
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax