Looks largely original to me. Although with anything 50 years old, some maintenance has been done.
The sticker on the valve cover was the engine code sticker applied at either the Windsor or Cleveland engine plant.
Since this was a California DSO it would have Thermactor, and that accounts for the second pulley. The ignition coil is on the intake (Thermactor models). The air pump bracket is still there. But the air cleaner and oil filler are the wrong style, indicating that these are probably not original to the car.
In addition to the radiator, the battery and cable, water pump, and shocks have been replaced. I like the extensions on the oil pressure sending unit.
Notice the early hood (no hole for hood turn signal light option). Notice the bare steel around the oval holes where the hood was hung. Indication of no repaint under the hood.
In regards to the original paint comment, I see that the door strikers are painted, so I would question that claim. Although under the hood the bolts are not painted, and neither is the caulk between the fender and inner fender, which appears to suggest that there was no repaint. Looking at the door jamb closely, it looks like someone did touch up limited to this area.
On the interior, I don't recall seeing the ring in the carpet that goes around the high beam switch on the floor.
In the trunk it looks like splices were added to the wire harness for both tail lamps. Never seen that before. Notice the remnants of glue used to hold down the trunk mat.
Not sure if we can repost pictures - I suppose it is public information at this point. If that is ok, we should probably do that since the eBay link will expire at some point.