Looking for some help with front coil springs

[68Mustang]

I bracket race but i know you stock and super stock guys know how to make a car launch.
I have a 68 mustang it runs 1.47 60ft 6.88 1/8th 99.3 MPH it is a ladder bar/coil over car. It launchs straight and picks the front tires up about 8 inches carries them out about 15 feet. It has 5 inches of front end travel. i would like it to pull them a little higher and carry them out another 15 feet or so. Was told that if i could get 6.5 inches of travel that the car would wheel stand even higher. Plus the car sits a little higher in the front than i would like.
Was told to change front springs that if i could get the front end down 1-1.5" that it would have more travel. What do i need to look for in a spring, someone said something about a spring the same height but weaker and not to put a shorter sprinng in that it would be worse, really didn't understand what they were saying.
I have the specs on the current springs if it would help, just let me know