This one has the rather unusual "corphwysont" ...why the "ph" ? I suppose it is some variant of "corpws" with the p aspirated to ph for some reason.... notice ysbryd turning into yspryd ..... a sort of internal reversed SM ... "irsm" .... rhyfedd. Mind you, it saved the carver a few minutes.
Ar ol ei holl flinderau dwys
Gorffwyso mae mewn hedd
Ymhell o swn y byd a’i bwys/
Heb boen yn llwch y bedd.
As you will see, there's a few slight differences, including that ff/ph swap we saw earlier