Insurance company wanting to "total" that would be some crooked shady shtif. You *never* know what you'll get into underneath it all, but bumper cover, fender, repaint the door, pull/pound out the wheel well and prime it, wheel and tire, possible steering linkage components... guesstimation 3-4k for a guy off the street... add another $500 or $800 for a woman off the street... 5k for a business, 6 or 7k for insurance and 14k if govt is paying for it...
You have to take care of your primary ride before considering something as optional as a project race build. We don't know anything about the condition of your current vehicle, but assuming its spent its entire life down South and away from the coast, rust is not really a factor. If the oil has been changed regularly and the engine solid, it is better to fix what you have versus start with a new car payment. (provided it is fixed right)
If all this costs you little or no money because the other party and/or their insurance isn't trying to bend you over, then this wreck changes nothing but time.