Is it permissible to join and partner in a commercial project after repaying a usurious loan with which it was funded, and how is a project established with ill-gotten money viewed Islamically?

Close friends should be advised to repent from dealing in usury. The usurious loan, despite its prohibition, transfers ownership to the borrower according to the sounder opinion, so it is permissible for him to establish a project with it. However, it is better and more cautious for the one in charge to avoid participating with them at all.