Although it is often rumored that Franco Zeffirelli considered Paul McCartney of The Beatles for the role of Romeo, he does not mention it in his autobiography, and as McCartney was 25 at the time, it is unlikely to be true, especially since the director engaged in a worldwide search for unknown teenage actors to play the parts of the two lovers. Leonard Whiting was 17 at the time, and Olivia Hussey was 15, and Zeffirelli adapted the play in such a way as to play to their strengths and hide their weaknesses: for instance, long speeches were trimmed, and he emphasized reaction shots. 
Enter ROMEO and JULIET above, at the window
Wilt thou be gone? it is not yet near day:
It was the nightingale, and not the lark,
That pierced the fearful hollow of thine ear;
Nightly she sings on yon pomegranate-tree:
Believe me, love, it was the nightingale.
ROMEO It was the lark, the herald of the morn,
No nightingale: look, love, what envious streaks
Do lace the severing clouds in yonder east:
Night's candles are burnt out, and jocund day
Stands tiptoe on the misty mountain tops.
I must be gone and live, or stay and die.
JULIET Yon light is not day-light, I know it, I:
It is some meteor that the sun exhales,
To be to thee this night a torch-bearer,
And light thee on thy way to Mantua:
Therefore stay yet; thou need'st not to be gone.
ROMEO Let me be ta'en, let me be put to death;
I am content, so thou wilt have it so.
I'll say yon grey is not the morning's eye,
'Tis but the pale reflex of Cynthia's brow;
Nor that is not the lark, whose notes do beat
The vaulty heaven so high above our heads:
I have more care to stay than will to go:
Come, death, and welcome! Juliet wills it so.
How is't, my soul? let's talk; it is not day.
JULIET It is, it is: hie hence, be gone, away!
It is the lark that sings so out of tune,
Straining harsh discords and unpleasing sharps.
Some say the lark makes sweet division;
This doth not so, for she divideth us:
Some say the lark and loathed toad change eyes,
O, now I would they had changed voices too!
Since arm from arm that voice doth us affray,
Hunting thee hence with hunt's-up to the day,
O, now be gone; more light and light it grows.
ROMEO More light and light; more dark and dark our woes!
Enter Nurse, to the chamber