Is it permissible to benefit from government aid, knowing that it is based on previous work that involved selling products containing pork?

If the information and documents provided to the granting authority are correct and free from forgery and deception, then there is no harm in benefiting from what they offer. The fact that it comes from taxes you previously paid does not preclude this. However, deception and fraud to seize what is not rightfully yours is forbidden, for the Prophet, peace and blessings be upon him, said: "Whoever cheats us is not of us, and scheming and deception lead to the Hellfire." Muslims must be good role models in fulfilling covenants and adhering to conditions that do not violate the Sharia.