Top tag: C5ZF H (H has been scratched out and D hand scribed. Not sure this tag is original to this carb)
Body numbers: C5ZF D
Casting number on bottom: 7-27-64
A C5ZF-H carburetor is a 2100. It should be C5ZF-D. You're correct, the tag is not original.
The casting number, 7-27-64, is on a lot of 4100 in the 65 time period. The tag would have the carburetor's assembly date.
- but will need a rebuild kit (needle valves are missing)
The originals were steel, replacements are brass. They work fine, just not concourse correct.
Jim