The Riley engine will fit in a Mini, but it will require some modification. The engine mounts will need to be modified to fit the Riley engine, and the exhaust system will need to be modified to fit the Mini's bodywork. Additionally, the fuel system will need to be modified to work with the Riley engine, and the electrical system will need to be modified to work with the Mini's electrical system.
Overall, it is possible to fit a Riley engine in a Mini, but it will require some modification. It is important to note that this modification is not for the faint of heart, and should only be attempted by experienced mechanics.
