In that last picture, it looks like the third elbow boss was either not drilled out or has a freeze plug pressed in.
Found one in the garage (well a few of different sorts) so grabbed a few pictures for you
The unused port is not drilled out - casting still there. Rear plate on this example needs to be cleaned, painted and machined surfaces returned then oiled
Look at the front of the pump
Look at the date codes - casting and assembly In this case this was made for an early 1966 289
Not to be critical but it needs to be mentioned not all of the details on that finished restored example will be correct for a car like yours so do your home work - don't just follow
And we all learn more (or at least should) as time passes