I don't think all PMCO aircraft will be fitted with an extra 6 inches of E+, but the 752 had 6 rows on the left side of the aircraft that have now been reduced to 5 rows. The stated pitch is 31, so 31/5 gives you 6 inches to be added to the 5 new E+ rows. that would be 36+ inches. The 738s will divide up 31 inches onto 5 row while the 739 will have an extra row to divide the 31 inches, maybe 35/36 inches on the 739. Of course this all can be different by aircraft type do to actual pitch in front of the exits and whether the bulkhead rows already have E+ legroom.
My guess is you'll find PMCO aircraft with 35-36 inches just like UA
has on differing aircraft in its fleet. Maybe an even occasional 34 inch pitch like SeatGuru shows on UA
744s on some of the E+ seating on the 772/736 international birds.