The single most important rule is rule number 1. It is an editorial event. It should be taken with a certain spirit in mind. You should play well with others. You should not behave poorly.
Rule #1. This Challenge is designed and run as an editorial event for a
privately owned magazine. As such, the rules and event should
be taken with a certain spirit in mind. In other words, all entrants
should play well with others. It will make the event much more
pleasant for all of those involved. Grassroots Motorsports reserves
the right to refuse entry to any individuals or teams. Individuals or
teams that behave in a manner that reflects poorly on this event or
the magazine will be immediately disqualified and their entries will be
removed from the editorial write-up.
That said. Read rule number 8 carefully.
Rule #8. All major body panels of the car that are being used as a foundation
for the Challenge car must be present on the car. This includes the
floor pan, inner fender panels, hoods, fenders, roof, sills, etc.
Bumpers may be removed or replaced. Full frame cars must retain
their full frame, while unibody or subframe cars must retain their full
floor pans, subframes and the like. Exceptions to this rule are listed
in Rule #9.
The last sentence says “Exceptions to this rule are listed in Rule #9.
Rule #9. Modifications may be made to the original unibody or body and body
panels and frame for engine and suspension swaps and
modifications, but only to the extent neccessary to perform the
change. This can include removing portions of the stock unibody
and frame and replacing them with corresponding sections from a
donor production car.
Read a little deeper, if you swap the engine or modify the suspension (Rule #9) you can remove portions of the body to the extent necessary to perform the change. If you use portions of the original body panels to complete the engine or suspension swap, the pieces are present and on the car (Rule #8). The extent necessary is subject to interpretation. However, you have to own the vehicle when the event is over and you want to invest your time in something you want (Rule #1). If it is not what you want, are you going to invest the time and make it worth writing about? (Rule #1). If you build what you want within the guidelines of the rules, the end product is more fun and you will likely finish it (Rule#1).
IMO, “extent necessary” includes safety, and chassis stiffness to handle the engine swap (more power) and suspension mods (more forces). Ultimately, Per has the only vote, but I want to see you compete. Your car is under $200X. Reread rule #1. FWIW, Rat Rods and Jalopies are appreciated in this crowd.