I use to race a 1969 Dart GTS 383 car that still had the original bigger torsion bars in it when I raced it with a 440 and 727, it had a good 8 inch race converter and 3.91 to 1 gears with 28.0 inch tall slicks. I played around with different things including moving the leaf springs into the sub frame, the car had the rear 1/4 panels butcher up pretty badly before I got so I had them straighten up and repainted the car before running it. When I had the leaf springs move in I also replaced the original springs with the Mopar SS 002 and 003 A body springs which help the 60 ft. and reaction times a bunch I also bought and install a set of Competition Engineering front drag racing shocks that had 90/10, 80/20 and 70/30 adjustments on them, I took the original front shocks and drill and drain them and put them in the race car trailer to do some A,B,A testing at the track some time. I was finally able to do that at one of the early, pre 2005, MATS races. I made 3 or 4 runs with the Comp Engr. shocks on the car on Thursday and Friday, I swap the drilled shock on before making another run and ended up laughing so hard after letting off at the finish line due to the car acting like a low rider bouncing the front end up and down The car did run a tiny bit quicker with the drilled shocks on compared to the Comp Engr. shocks set at 90/10 but I couldn't stand the porpoising so I changed one side(left front I think) to the Comp Engr to stop the bouncing, which worked fine
That car wasn't very fast, I think it ran a best of 11.17 at 122 MPH in the 1/4 at that race but I could go rounds in it and win some races
Test, test and test some more to learn as much as you can, good or bad