I was just looking at this picture of the shock tower:
And then comparing it with the picture of the Kirkham shock tower on page 851 of the SAAC registry.
Unlike the above picture, which has the number going from top to bottom, the Kirkham number runs left to right closer to the bottom than the middle.
The Kirkham shock tower plate also has 2 threaded holes on the right side (could be mounting a horn?), which are not found above.
If the picture in the SAAC registry is typical of where Kirkham stamps their serial number, then this does NOT appear to be a Kirkham shock tower bracket with the number ground off and replaced.