The version in Songs of Scotland is only a bit different:

For instance:
BUT purest monarchy, not THAN
I'll call a synod in MY heart (which is interesting as that changes the entire meaning)
AS Alexander I will reign
WHO does not dare

And there is an additional verse (After the Alexander verse) and the last has more difference than the others:

But I will reign, and govern still,
And always give the law,
And have each subject at my will,
And all to stand in awe:
But 'gainst my batt'ries if I find
Thou storm or vex me sore,
And if thou set me as a blind,
I'll never love thee more.

But if no faithless action stain,
Thy love and constant word,
I'll make thee famous by my pen,
And glorious by my sword.
I'll serve thee in such noble ways,
As ne'er was known before;
I'll deck and crown thy head with bays,
And love thee more and more.

It's noted [From Watson's Collection, 1711.] Interesting differences from Wedgwood's version...