We will get to the second book soon Aussie, thanks for the reminder.
To be sure the front down tubes of the Roll Cage fit well, I set the dash pad in temporarily.
With the dash pad in, I could see that the mounting points for the bottom of the forward tubes was off.
As a solution I decided the best thing was to make platforms for both sides.
This allows for the tubing to sit straight and parallel with the frame of the car.