The re-enforcement will consist of a piece of steel angle spanning the from the front support bolt to the 3rd support bolt from the front. The support bolts will go through this angle.
This angle is then attached to two attachment points by three 16mm d round steel bars.
The attachment points
I have chosen are the the old back seat bolt locations.
The steel angle will have to be notched, bent and welded to fit the contour of the roof