The VIN is beyond the normal range for an 03D body tag date. That can happen if the order was released at Fisher and immediately went on hold. That happened with our '67 Z/28 project; 06E tag built mid-July with 07B cars. Original engine was V0706MO. Obviously, someone checked and found no 302 engines in stock; car could not be built. So the build order went on hold until MO engines were in stock.
In this case tag looks ok, rivets fishy. Only reason an L48/auto Z11 would have gone on hold is an out of trust dealership. Probably would have built it anyways. Tag may have been swapped from a scrapped Z11. Some signs are standard seat belts, drum brake master, no ZL2 wiring. Like to see the area around the fuse block.
No matter, it’s a hack resto. Bad body work, repro/non-OE/missing parts, 48” PS hose lying on the exhaust manifold alongside a plug wire. Mis-matched horns? Geez…