Is the inherited portion considered permissible or impermissible if I inherited land and my unjust paternal uncle sold it for less than half its value, knowing that he was known for earning unlawful money and has now repented?

There is no blame upon you for taking your share of this money, nor for accepting a gift or present from your uncle. This is because, according to the preponderant opinion among scholars, it is not forbidden to deal with a person whose money is mixed, where lawful and unlawful wealth are intermingled.