What are the some good negative earth points on a V8V roadster?
(In particular, around the trunk and centre console)

 

Not sure there are any designated earth (ground) points in those areas, however if a good ground is required, I would suggest running a wire to the negative battery cable body ground point directly beside / below the battery.

 

Is the fuse box for the roadster in the trunk? Should provide plenty of points you could use for a ground.

 

Battery is always the best, but there should be one near all the fuse boxes. Not sure about center console.