The epitaph begins, as is customary, by telling us all about Grace's distinguished male relations, then becomes rather more interesting...
We don't know what she died of but whatever it was allowed her to remain conscious right up to the end- and during those final hours she had what we now call a near death experience- and was able to relay what she was seeing to the watchers round her bed.
Anyway, here's what we're told (spelling modernised)
Having ye day before her death most devoutly received ye holy communion (which she said she would not have omitted for ten thousand worlds) she was vouchsafed in a miraculous manner an immediate prospect of her future bliss for ye space of two hours to ye astonishment of all about her, and being (like St Paul) in an unexpressible transport of joy (thereby fully evidencing her foresight of the heavenly glory) in unconceivable raptures triumphing over death and continuing sensible to ye last, she resigned her pious soul and victoriously entered into rest.
Under the main text it says...
Her dear and afflicted mother whom God in mercy supported by seeing her glorious end
erected this monument. She being the last of her surviving issue.