How to get my script to work with Ultimate FPS camera

Hi guys, so Ive made a script which lets you break and place blocks (with varying speeds, theres also a shovel which increases the speed) and it works fine, but Ive brought the ultimate fps camera, and was wondering if there was a way I could get it to work with it, perhaps by switching modes (1 mode takes you to the ultimate fps, the other to this script). Also, my terrain isnt made of the blocks, so I also need help making the script only be able to break blocks Ive placed. many thanks

 //Misc
 var BlockSelected : float = 1;
 var Range : float = 20;
 var Crosshair : Texture2D;
 
 //Shovel (0)
 var WoodShovel : GameObject;
 var WoodShovelDestroyTime : float = 0.5;
 
 //Grass (1)
 var GrassBlock : Transform;
 var HeldGrassBlock : GameObject;
 var GrassBlockDestroyTime : float = 1;
 
 //Stone (2)
 var StoneBlock : Transform;
 
 
 function Update () 
 {
 
 
 // changing items
 if (Input.GetKeyDown(KeyCode.Q)) 
     {
         BlockSelected -= 1;
     }
     
 if (Input.GetKeyDown(KeyCode.E)) 
     {
         BlockSelected += 1;
     }
     
 if (BlockSelected == 0)
 {
 WoodShovel.active = true;  
     }    
     else WoodShovel.active = false;
     
     if (BlockSelected == 1)
 {
 HeldGrassBlock.active = true;  
     }    
     else HeldGrassBlock.active = false;
     
     
     //adding and deleting blocks
 if (Input.GetMouseButtonDown(0  && WoodShovel.ShovelSelected == true) || Input.GetMouseButtonDown(1))    
     {
         var Hit : RaycastHit;
         var LookingDirection = transform.TransformDirection(Vector3.forward);
         
         if (Physics.Raycast(transform.position, LookingDirection, Hit, 20))
     {
         
         if (Input.GetMouseButtonDown(1))
         {
         
         if (BlockSelected ==1)
         {
         var GrassBlock :Transform = Instantiate(GrassBlock, Hit.collider.transform.position + Hit.normal.normalized, Quaternion.identity);
         GrassBlock.tag = "GrassBlock";  
         }
 if (BlockSelected == 2)
 {
 var StoneBlock :Transform = Instantiate(StoneBlock, Hit.collider.transform.position + Hit.normal.normalized, Quaternion.identity);
         GrassBlock.tag = "StoneBlock";
      }    
      } 
     
     else
     {
     if (BlockSelected == 0)
     {
       Destroy(Hit.transform.gameObject, WoodShovelDestroyTime);
         }
         
         if (BlockSelected == 1)
     {
       Destroy(Hit.transform.gameObject, GrassBlockDestroyTime);
         }
         
             if (BlockSelected == 2)
     {
       Destroy(Hit.transform.gameObject, 4);
         }
 }
 }
 }
 }
 
 function OnGUI()
 {
 var Width = Crosshair.width/2;
 var Height = Crosshair.height/2;
 position = Rect( (Screen.width - Width)/2, (Screen.height - Height)/2, Width, Height);
 
 GUI.DrawTexture(position, Crosshair); 
 
 
 }