Leaf springs flat - 69 Barracuda

Just purchased this car, the leaf springs are flat. Originally a slant 6 car now with a 318. Won't ever see the track but I do like my 0-60 getting on the highway. What should I do with the leaf springs? Looking it up I saw that HD springs would be on small block Formula S cars. What should I be looking to get to fix this squat?

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