I've made a best-guess version making use of all of your posts and my part-of-song transcription. It can't be right yet, but it looks an improvement to the version from Peace's link.

Wolfgang

TWO-SHILLELAGH O'SULIVAN

SPOKEN: Two-Shillelagh O'Sullivan, hah! He was a mighty man. Listen to what I'm telling you now: mighty, mighty man, Two-Shillelagh O'Sullivan.

1. There's many a man that rode a horse across the western plain.
There's never been one like the Irishman, O'Sullivan was the name.
He never packed a shooting iron. The need he never felt,
With two shillelaghs always there, a-hanging on his belt.

CHORUS: Yippee ky i o, me buckos, begorrah and yippee ky o,
Two shillelagh O'Sullivan, he'd give any man a go.

SPOKEN: Hah, the shillelagh! Hah! As you know, we call it the Tipperary rifle. You never have to reload it.

2. This bronco-busting Irishman from the heart of Erin's isle,
He was after living peaceful-like. He always wore a smile,
But when the smile was leaving him, in a fight he'd come unwound.
That says for any crossing him they'd wind up on the ground. CHORUS

SPOKEN: Why, he was so strong, O'Sullivan, he could put his right hand in his own left hip pocket, and he could hold himself out at arm’s length. (No man could do that.) It's O'Sullivan I'm talking about. (Oh, well, he could.)

3. At throwing the rope for branding calves, he was a mighty man.
At throwing his two shillelaghs now, the fastest in the land.
‘Twould ’a’ been a sad mistake, me boy, to reach for a 44.
Before you could get the hammer cocked, he'd have you on the floor. CHORUS

SPOKEN: Did you know O'Sullivan played the Irish Harp? No, o sure, and he did. he put 75 strings on his two shillelaghs, he'd stretch them out 24 feet, and he had four leprechauns dancing on them to make the music. Oh, the wonder of it! Sure and he would charm the coyotes out of the hills.

4. Across the range from morn till night, he rode for days and days,
A-fixing fences here and there, and a-picking up the strays.
A cattle spread he really built, as big as Ireland,
Where he could range a million head, and a shamrock be his friend. CHORUS

SPOKEN: A bit of his lip, the back of his hand, the toe of his shoe to boot is, Oh, Two-Shillelagh O'Sullivan. Now if you're ever riding through the sagebrush wilderness, and you suddenly come upon acres and acres of shamrock sprinkled with stardust, well, you'll be after knowing, that you've just arrived at the O’Sullivan spread, known as the Lazy Leprechaun's spread. Stop in, won't you? Sure and they'll give you a belt of Bushmill’s.