There are a lot of things you can do to start squeezing numbers out of it. A looser converter would probably help. Is the car hooking or spinning? If you're spinning, getting the suspension sorted to dead hook could pick up a few numbers. Shift point may help, if your motor is making power over 5600 RPM. Gear change may help but again only if your motor will support the higher RPM. My 383 was built for low end power and it quits pulling around 58-5900 (by design). Loosing some weight will pick you up quite a bit too. Depending on the setup, going to a different tire will pick up a tenth or more. Less rotating mass = faster ETs. Radials can be heavy wasting a lot of power.