Please forgive the inconvenience.
Attaching a gzipped patch file
ensures the integrity of patch file content.
I should have presented only the idea
rather than a patch for the implementation.

I concur dd is already suited to the task.

Please consider

| sed 's/^/if=/' | xargs -r --max-lines=1 dd iflag=direct  # in contrast
with
                   | xargs -r --max-lines=4096 cat -d --

Invoking dd 466059 times costs only a slight performance decrease
as compared with invoking cat 114 times.
However, this example probably represents rare usage for cat.

Thanks for granting the time and consideration.