To give some clarification on what I said about the floor. The .035 steel flooring must be welded on both driver side and passenger side to the pipe (on the inside of car) and not riveted as I would prefer, so when NHRA decides to add a piece of pipe or up size one, you would have to destroy the flooring and anything in your way to do it. As for the chassis design Ash is correct that each chassis is like a snow flake to clear your car body and fit you. It has been my expeirence over 25 years of building my own cars from scratch (and quite a few others) that over 80% of the job in time is coming up with a design that works with the chassis and laying everything out accurately, within perfect would be OK, not within 1/16". Only 20% of your time is fitting and welding which is the gravy part. The struts that I mentioned that are not likely going to like the street were the Strange, Lamb type agresively valved for drag racing. The rear shocks will need to be street quality also to survive street driving of any regularity.
The SFI foundation has books that they sell for guys like you and I that just need the rules to build your own car. I think Zip highlighted that for you in his entry. These books do not tell you how to build the car, They are for tubing sizing and angle limits and locations which are very general. Every chassis will look different than another with the same classification level depending on the body they fit. Your finish chassis does not have to be the exact same as the books examples they provide. They are just examples and the writing part is the most important part to follow. You will likely need to check with a chassis builder now and then and possibly a NHRA tech inspector to ask for interpritation of the book for certain things possibly.
Don't be intimidated by the the job, It is very rewarding work and as a welder you can save the bank by doing it yourself. You are trying to build a car that would cost you $65,000 to order and pick up and there will be a lot of work and learning. Just get a good plan and make it happen for yourself. Remember that SFI doesn't make cars or design them, they make safety rules and strength requirements for the driver only. The car design is your baby.
Bruce