So, just my opinion... The font looks like a generic hardware store stamp... But being a 68 the whole VIN stamp thing was new & plants were still working on the details.... My computer that I had saved a number of 68 VIN stamps to crashed awhile back... Currently I have to search the web for photos... My recollection of 68 Hamtramck VIN stamps they were similar to the Belvedere stamp...
Belvedere Stamp
View attachment 1430298
Lynch Rd Stamp
View attachment 1430299
I couldn't find any 68 Hamtramck stamps on the web... I'm sure they are out there... I didn't find it..
But another thing to notice it the tilt/cant of the letters... There is some up & down movement of the Belvedere letters but they aren't tilted... The Lynch Rd stamps aren't tilted & actually are pretty much vertically matched too...
The O/P's numbers are tilted quite a bit... Like they were stamped free hand... Anybody here actually believe every letter/number on every engine was individually stamped??? They were held in a fixture that kept them clocked...