Toru’s goal in JoJo Part 8 was to use the New Locacaca to create a revolutionary medicine, while also pushing rock humans into a position of greater power over humanity.

In simpler terms, he wanted:

  • Profit and influence through the Locacaca business.
  • A world where rock humans could rise above humans in status and control.
  • To use that power through his Stand and the medical project tied to the New Locacaca.

So the short answer is: money, power, and species dominance for rock humans.