Sorry, but you're basing your project on a flawed theory. What you are purposing is based on a white paper written by Peter Gutmann who purposed that weak and strong traces of overwritten data could be read back using MFM technology.
His theory was quickly debunked and proven completely wrong. He actually had no idea how hard drives really work. No algorithms or scripts exist for what you are suggesting because it's impossible. Even if it were possible, it couldn't be done through software but would require the use of MFM machinery.