First off nice car!! secondly get that driveshaft fixed!!!..with that converter i'd be launching at 2800-3000,what are you running for tire pressure?? it can play a big part in getting you out of the hole,i'd bring that shift point down to 6200,i'm guessing you have frame connectors,drag shocks these will also help a "LOT" getting you off the line...Just for comparison my '70 duster with a 030 over 360 .513/.533 cam,Edelbrock heads,3800 stall converter leaving at 2800,with 4.30's, runs high 11.70's-low 11.80's and 60's in the low 1.60's...