I've never found any minor chord that works for me in this song.

If I may borrow Roughyed's words:) (Although I tend to play it in D!)

(D)I am a little beggarman, a begging I have (C) been
For (D) three score years in this (A) little isle of (C)green
I'm (D) known along the Liffey from the Basin to the (C) Zoo
And (D) everybody calls me by the name of (A7) Johnny (D) Dhu

Of (C) all the trades a going, sure the begging is the best
For (D) when a man is tired he can (A) sit him down and (C) rest
He can (D) beg for his dinner, he has nothing else to (C) do
But to (D) slip around the corner with his (A7)old riga(D)doo

Certainly I can't find any notes that grate played this way but perhaps played in G or A there may be.

In the 2nd line I have A rather than A7 as the three notes there(li-tle-isle) are E-C#-A so they form a run down from the 1st to the third strings.

Played in G using the chords given by Roughyed it sounds OK but to me there is still something not quite right. It just goes to show there are many ways to skin a cat and even more ways to play a tune.