Look at the one I installed in my 1989 Mustang.
Follow this link for MANY MANY more photos.
http://www.dariusrudis.com
Look into how others have done it, BEFORE you finish welding!!!
Things to watch:
Mount main hoop on the floor, or rear subframe (allows for more legroom).
Diagonals may affect headrest.
Doorbraces fit above/below your elbow.
Rear downtubes in an X-pattern or straight back, then mounted to rear shocktower or frame...