Greg your car would fall under SFI 25.4 not 25.5. 25.5 is for stock firewalls and steel floors, both are good to 3600lbs. You need the entire F/C cage how its configured will depend on where your helmet sits in relation to the main hoop. You will need x bars in the floor and a kidney bar and 6C ba(Bell housing area, it can be one piece or three just depends)which can be removable as well. I would suggest ordering a 25.4 SFI spec book and follow it. As for where to buy the tubing, do you have the capability to bend the tube? If so most any big chassis shop can help you. I buy a lot of my stuff from RJ Racecars, but also use MCcamis, Bickle, Rhoades racecars and Tin Soldier. Just depends on what I need.