Are you sure it is a P and not an S ?
There were two types of S mint marks used
on the 79-S Still would need a pic though.
Also the proper term for your possible "near date"
is wide rim or wide border not near date, as the position
of the date did not change on these or the following years.
Just that the border on the 1980 was wider than the 79.
Here is one of mine for reference. Very easy to spot the difference. Just look at a 1980.

There were two types of S mint marks used
on the 79-S Still would need a pic though.
Also the proper term for your possible "near date"
is wide rim or wide border not near date, as the position
of the date did not change on these or the following years.
Just that the border on the 1980 was wider than the 79.
Here is one of mine for reference. Very easy to spot the difference. Just look at a 1980.




















