McCloskey in south Donegal

I am looking for the place that my ggrandfather emigrated from in Ireland.

Francis McCloskey b 1830 somewhere in Ireland.

emigrated to the US after the famine,

Married in Philadelphia, PA in 1863.

was in the US Navy during the American Civil War (1860-1863), worked in the merchant marine after that. Disappeared in 1873.

His network of friends and family are what I'm trying to use to pinpoint where he may have come from.

A fellow sailor was Roger Cassidy, who married Francis' sister.

Roger's sister Mary married Anthony McBrearty.

I believe that McCloskey, Cassidy and McBrearty came from the same area and migrated to the same place in Philadelphia.
 

McBrearty comes from Killibegs, Donegal.

I see in the 1834 Tithe Applotment books an entry in Donegal for a McCloskey. When you look at the image, it says Cassidy & McCloskey.

This page was for RAPHOE.

Can anyone in south eastern Donegal find a McCloskey household in the 1830s?
What about now? Any McCloskeys in southeast Donegal today?
Is there any place where McCloskey, Cassidy and McBrearty are in close proximity - clustering around Donegal town, perhaps?

Are there emigration records specifically for Donegal?

I'm looking for leads and new places to search.

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I see from Griffiths that there was a Francis McCloskey in DRUMROOSK, WEST.
This is likely to be my Francis' father as I see different immigration records in the US in the 1850s.

I also see a James McCloskey in Inver, townland of TULLYNAGREANA.
There is a strong naming pattern in my family for James and Francis - every generation in the US has BOTH names. So either the James or the Francis in Griffiths could be fathers or uncles of my Francis who emigrated to the US. There is a James McCloskey in Philadelphia who was godfather to one of Francis' children so I assume that this James is either a brother or a first cousin.
Given the fact that there are no census records of the famine years, are there any Catholic church records for this civil parish? Any school records?

I mention four names - McCloskey, McBrearty, Cassidy and Lafferty (Laverty in Ireland?).
They all intermarried in Philadelphia. Are there any Laffertys in this parish?

Thank you all for your help!

Colleen