you will have to redrill the chassis for the .21 engine, the case is larger, also you will need a different header and pipe, adjustable engine mounts from the monsoon would be a great help also. You will also need the whole assembly from the flywheel forward (clutch bell, shoes, washers, nuts, etc) I have done it and its insane but you will go thru spur gears like crazy since it wasnt really designed for a big block engine.