What part dont you see as being the case… the Pope as the successor of Peter, or Mary being full of Grace?
The succession of the Papacy can easily be traced back through to the apostles, and Peter was the bishop of Rome, just as the Pope is the Bishop of Rome.
If you dont believe that Mary was full of Grace, then you reject scripture, and we must have a whole other conversation.
(Luke 1:28 NASB) And coming in, he said to her, “Hail, favored one! The Lord is with you.”
“favored one” = G5487. charitow, from G5485; to make graceful, endow with grace:-- favored(1), freely bestowed(1).
This is the same root used to describe Christ in John 1.
(John 1:14 NASB) And the Word became flesh, and dwelt among us, and we beheld His glory, glory as of the only begotten from the Father, **full of grace **and truth.
In addition, scripture tells us that ALL GENERATIONS will called Mary blessed.
(Luke 1:48 NASB) "For He has had regard for the humble state of His bondslave; For behold, from this time on all generations will count me blessed.