Opinion: I'm just a truck racer, and member of the SCTA, NOT an inspector or official -
Your first step is to get a rulebook from SCTA-BNI.ORG and read it page for page, ESPECIALLY the front.
There is a lot of safety equipment to buy. I spent about $20k on safety equipment for a pickup. You could do it for far less, but it's still not going to be a cheap date or simple.
If you are good with the universal safety equipment rules, then here's what the book says:
Production Pickup allows a shell so I THINK you could do it.
5.E.4 /PP "Aftermarket bed caps are allowed but should not offer an aerodynamic advantage".You have two possible paths:
1) Contact someone from
http://scta-bni.org/contact.html , I think it's Mike Manghelli, and get a decision if it qualifies as PP. Send pictures. You should keep any correspondence and pictures in your logbook (you need a SCTA logbook for your truck at all times).
2) Just show up with PP on the window, and register it as PP. You might get protested, but if it looks like a truck, I doubt it.
Now, be aware, a normal Sedan Delivery is NOT a truck I've been told. If it was based on a car chassis, it's a car. El Caminos are cars, my old '57 Ford Sedan Delivery is a car. The only exception is VW Rabbit trucks as far as I know. From what I remember a 65 Chevy Panel is a pickup with a van bed incorporated. It has the truck frame and nose. A 57 Ford SD is a 57 sedan with van bed on it.
Note, your safety rules are based on the existing record or minimum. 128mph for Bville and 118 for Elmo.