The stamp your looking for is not specific to San Jose plant since it was applied at the engine plant. Will move this over to the 69 section for more eyes to see it.
There are a number of OK valve cover stamps used at the engine plant that assembled the 428 CJs though the one Jack offers is the most common IMO. The other versions might have been assigned to inspectors that filled in for the current ones and may have been regular inspectors in prior years based on other patterns we've seen.
On engines from other plants and other years the size and design can differ some so for others seek out the best available rather than settle for just close
Someone will notice