GUIText Instantiation to show at Asteroid position

Hi guys,

I've finished going through the Space Shooter/Asteroids tutorial and now I am trying to tweak the game to keep learning.

What I would like is for when the Asteroids are destroyed to have the number of points for that asteroid to be flashed on the screen at the position of the asteroid. I am having some issues with this and I have tried to follow the advice given in this question but I am not getting anywhere!

I have DestroyByTime on the GUIText prefab which I have tested separately and I know will remove the points after a given amount of time but I can't get the text to display where I want it to.

Like I said I have tried to get the code in the linked question to work but I end up crashing the game so I have included a stable version of my code below (I tried to copy how the explosion was Instantiated):

 using UnityEngine;
 using System.Collections;
 
 public class DestroyByContact : MonoBehaviour
 {
     public GameObject explosion;
     public GameObject playerExplosion;
     public GUIText pointsText;
     public int scoreValue;
     private GameController gameController;
 
     void Start ()
     {
 
         GameObject gameControllerObject = GameObject.FindWithTag ("GameController");
         if (gameControllerObject != null)
         {
             gameController = gameControllerObject.GetComponent <GameController>();
         }
         if (gameController == null)
         {
             Debug.Log ("Cannot find 'GameController' script");
         }
     }
 
     void OnTriggerEnter (Collider other)
     {
         if (other.tag == "Boundary")
         {
             return;
         }
         Instantiate(explosion, transform.position, transform.rotation);
         if (other.tag =="Player")
         {
             Instantiate(playerExplosion, other.transform.position, other.transform.rotation);
             gameController.GameOver ();
         }
         else
         {
             Instantiate(pointsText, Camera.main.ScreenToViewportPoint(transform.position), Quaternion.identity);
             Debug.Log ("Position: "+Camera.main.ScreenToViewportPoint(transform.position)+", Rotation: "+Quaternion.identity);
         }
         gameController.AddScore (scoreValue);
         Destroy(other.gameObject);
         Destroy(gameObject);
     }
 }

Lastly! Once I have the GUIText is created I need to set it's text value to scoreValue so any help with how to set the text value on an Instantiated GUIText object would be much appreciated.

Sorry for such a long first question!