You're looking at $1,000 for the headers/intake/carb/ dizzy.
Is the rest of the package worth $2,000?
If the 8 3/4 is posi and ready to run as is there's another $800-$1,000 .
Is a 383 long block of unknown origin and 727 worth another $1,000? If the engine is solid I think it could be a nice deal for $2,500 to $2,800. Lots of unknowns and "ifs".
I would find out a bit more about the engine internals and consider offering $2,500 for the lot and let it unfold from there.