That's right.
Generally it is Reg = 2 PIP, Irr = 3 PIP.
But that is only for "wide" groups. For columns it is 1 and 2 PIP respectively because d) says a group "other than a column".
Also remember that Irregular Clumsiness doesn't count for Light Troops, and Cv(O) in good going.
So a column of Irr Ax, LH, Ps or Cv(O) wheels for 1, and a wide group of the same wheels for 2.
John