Engine stabilizer bar
The V8 just fits under the bonnet and between the wings. It is mounted as low as possible. So rocking of the engine should be prevented. There is a proven way, that the Rover P6 also uses: an engine stabilizer bar. You could take one of a P6 and fit it to the B.
Here are some pictures from chaps who fitted such a bar.
These two pictures are from Paul's car.
Here we have two pics of the engine stabilizer in Andrew's car.
