From looking at the engine, I don't think it is original, unless it is a very early 86 model. Granted, it's been a while since I tinkered with a mouse motor, but I think Chevy switched to the center bolt valvecover in 1986. That engine has the traditional four bolt ones.
The engine is also missing the AIR injection tubes on the exhaust manifolds. I suspect that they were removed since they are a part of the poor emission control system on that car.
I also don't know if someone would put all that money into the stock 305 since it was a rather weak-performing engine. I actually had a Performer carb, intake and cam in my 83 Monte 305, but that was after I blew up the 350 that most of those parts were purchased for. :brick
It is nice to see the air conditionaing and cruise control stuff is all hooked up and hopefully functioning. The rest of the car looks sweet. The lines are very clean and the monochromatic white adds a lot of "smoothness" (sorry Fuzz) to that car.