You won't be able to do a whole lot about his acceptance of the bit until he accepts seat and leg cues. He's heavy on the bit and has poor acceptance of it b/c he hasn't been trained to carry himself properly or respond to the rider's aides. If he doesn't understand leg and seat cues, you won't be able to do the circle exercise I posted about. He won't step under himself, he'll just fall out of the circle trying to go faster when you put leg on. Which, of course, would mean he's being a good boy b/c that's what he currently understands. Start with the basics and train him properly, the bit acceptance will likely come along on its own.