Start cutting some weight on that 76. There is a lot to lose on a good diet with those heavier sport styles that year. Take that front bumper off and lighten it would be my first on the list. Use the skin and make tour own light weight brackets. Taking things off of the car is free. Every 100 lbs. is at least a 1/10 on a car running 13's. A 9 second car won't gain as much.
Decreasing reciprocating weight gains are much more. Light weight rear tires and wheels, even a lower profile and narrower tire helps. lighter drive shaft. Put a shut off on the alternator. Electric water and fuel pump.
Stop eating bread and potatoes.LOL