You can build a rollcage from specs and photos in the NHRA Rulebook that will allow the cage to be certified down to 8.50 e.t.
If you plan to go faster than that, you'll need to contact Sema Foundation, Inc. and buy their plans that fit what you'll be doing with the car. Here's the Rulebook for $10.00.....
http://store.nhra.com/product.asp?3=54

Here's a paper I wrote on installing a rollbar to get you started....
http://streetmachinesoftablerock.com...opic.php?t=217