// Assign manually a font from the inspector to the GUIText
    var font : Font;
    guiText.font = font;

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public Font font;
    void Example() {
        guiText.font = font;
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public font as Font

    def Example():
        guiText.font = font