The easiest route to build an Essex Wire Cobra is to start with the very nice Monogram kit which includes appropriate Good-Year Sports Car Special race tires.
Gunnar, I scratch built the dual batteries, support tray and anchoring brace.
Positive cable typically connects to the starter solenoid, Negative cable to a ground on the frame.
Very few 427 Cobras competed with dry sump lubrication. I attempted to replicate this with my build of CSX3016 which was a 427 that ran a dry sump system. The puke or overflow reservoir is the black cylindrical tank on the fire wall behind the engine. The larger tank (which I scratch built) on the right side foot well is the remote oil reservoir. My build is based on the 1/25 scale Sunny kit.
The fill for the remote reservoir appears in the front right fender. The tell for a dry sump car.
You need to determine what time period for each chassis number you want to build as these cars evolved significantly over time. This will help you determine what details would be most accurate.
I agree with Rex (vamach1) the Revell kit is a more accurate kit to start with.
Lap belts only typically. Shoulder belts may have been added during the car's evolution.
Cooling fans where primarily used for street cars and not (typically) used on competition cars.
As an example there appears to be no shoulder belt in this photo.
However in this photo there does appear to be a shoulder belt.
That is why it is best to select a time period you want to replicate.