Pit Help.

[TommyHotWheel]

Ok Pit Owners, I need some advice and what to look for as far as problems and such with a Pit. I rescued a Pit Mix...looks small, beagle or lab? He was tied to a rope about an inch and a half around, beaten(broken ribs and sore legs) and severely malnurished. He chewed thru the rope and was wandering, he was finally picked up by the lady that works with my wife, eating garbage thrown from cars on a busy stretch of highway. He was taken to the vet, malnurished, worms...very skittish. He seems to be very playful, behaved and gets along with other dogs(waiting to see how he gets along with the king...our Min-Pin). He was an outside dog, the girls want to see if he can be housebroken, they want a guard dog. Any advice? He is about 9 months and a brindle coloring with brown eyes and natural ears. Pics later. Thanks.