If you want to race at the salt you need to follow the rules in the SCTA-BNI rulebook. I suggest you take a look again at the highlighted in red sentences:
5.A SPECIAL CONSTRUCTION CATEGORY
This category is the pinnacle of the straightaway racers art. It contains three main groups. In the automobile group are the unlimited Streamliners and open-wheeled Lakesters with a 4+ wheel configuration and in the motorcycle group are the Streamliner and Streamliner Sidecar classes. These classes allow both blown and un-blown, gas or fuel engines. These are all-out straightaway vehicles with non-stock engine blocks allowed, (with the exception of specific Vintage engine classes). Innovation is encouraged, within the rules. Modified production bodies are forbidden. Four-wheel drive is allowed in the automotive group only.
It is strongly recommended that all new vehicles be submitted for a pre-event inspection by appointment with the Technical Committee. If not practical because of distance, photographs and drawings may be submitted to the Technical Committee Chairman, see Section 16.
5.D.1 Competition Coupe & Sedan - /BFCC, /FCC, /BGCC, /GCC
This class encompasses production coupe or sedan bodies unaltered in width or contour. Streamlining ahead of and including the cowl, channeling, belly pan and skirts and spoilers, as defined in Section 4.CC. is permitted. One of the following modifications SHALL be done to be considered in this class:
1. Top shall be chopped.
2. The vehicle shall have a full belly pan.
3. The body from the cowl forward shall be
lengthened a minimum of 12 in.
4. The engine shall be set back a minimum of 25%
of the wheelbase. The engine setback
cannot exceed 50% of the wheelbase.
Other than top chopping, no modification to the body is allowed. Minimum vertical windshield height is 5 in. The front and rear chop shall be equal. Window openings may be covered by flat plates on the outside of the opening or left open. Driver shall sit COMPLETELY ahead of the rear axle, inside the body and behind the engine, except in rear-engine cars using the original engine LOCATION. Driver exit hatches in the roof are recommended but shall not change the contour of the body. Cars in this class are considered in the Modified category and shall comply with the general rules of the category.
I would think that MSA guys would tell you to follow the rules. Just because you build it doesn't mean you can run for class records.
DW