I have made a few modifications for ease of installment. Bellow is a picture of the actual helmets in storage you can see the torch is held in place by wire, So I have replicated the system to attach to the shield.
Below is the wire set up that you can use to install your torch to your helmet shield. Note this is a different torch set up. You will need 1-1.2mm wire to slide inside the 2 holes of the torch to secure it to the helmet shield.
Type of torch that will fit inside the print any torch that has diameter of 15mm and a maximum lenght of 98mm, here is a link to the torch in the picture.
Finished torch on the Rebel Helmet.
The torch shell will be available at shapeways.