Are the tires actually slipping or spinning? If you are hooking, then most improvements would come through optimizing the converter, gear and carb tune-up. Accelerator pump circuit is critical, especially for a footbrake car. It's always a matched "package" that works together for best performance.

Posting more combo info as well as MPH can help determine what kind of HP you are making and what the '60 potential may be. Someone may have a similar combo.