If you’re gonna build your KITT replica, you’re gonna need parts. Some more, some less, depending on the general condition of your Firebird and depending on how far your want to go with the project. This usually correlates with the time and budget you have to get it done. Long story short, I would advise you to start with the mechanical part, the actual restoration of the car before diving into the specific Knight Rider related parts.
Here’s my take on where to find parts to restore your Firebid…and also several other american icons.