I had a blm mustang filly I adopted at her age and the way I halter broke her was by putting her in a 10 by 10 pen and using a pole to touch her - I could stand in the middle and no matter where she went I could touch her with it. When she tolerated it I backed away (release of pressure). Did that for a while until I could touch her, then worked on that for awhile. Once you can touch them with hand an pole, you make pretty fast progress from there. Good luck, with him - he is a cutie.
I also like the name Chance (because you took a chance on him).