The RC parish records for Dunhill & Fenor only start in 1829 so it seems unlikely you?ll find your ancestors baptism details if they were born before that date.
There?s quite a few Power households listed in Griffiths Valuation for Dunhill in 1850. You might want to use them as the basis for further research, perhaps ? given the fishing links ? focusing on the ones around harbours.
There were 52 Power households in the tithe applotments for Dunhill in 1831:
However as with Griffiths you need to bear in mind that these are not comprehensive lists of every person named Power, just heads of households, and in the case of the tithes only where the person had some land.