FWIW I have seen MANY 1970 Birds ( from 6 cyl to Ra cars) built from 12C to 04D that have a "9" in the Vin stamped on the firewall , NOT a correct"0"
I believe some of the Engine stamping issues happened due to the fact that Pontiac built engines for the 1970 model year cars many months before 1970 production began.
They were also building "69" engines at same time.
I am pretty sure they had issues with the "0" all over the place.. Broken stamps, missing stamps, not enough stamps.
On THIS car, since its been gone over already, what I would do is drain the oil, let it sit, and SCOPE it . Even with the partial windage tray ( if its on there), you should be able to see if its a 4 bolt.
If it is, Its probably original as rest of numbers seem to indicate It is.
That screw up in stamping looks a but much for a re stamp.
If you have ever seen the last SD built ( yellow car) , that engine stamp(s) is a disgrace and far exceeds this one.
Good luck..
