well done, both you and scamp, it's lovely to hear of a dog getting proper attention and responding well to it. i myself have 'rescued' several adult dogs with good results, they all respond to proper management, and love you all the better for it i think.
and as for the bit about not being 'steady' around sheep and hens, given time that will sort too, i have a belgian shepherd that was allowed to roam free and chase whatever she liked, but now she lives with geese, ponies and hens, and has had to learn to behave, which mostly she does, the ponies sometimes get the opportunity to remind her to leave them alone though!,
he sounds like a nice boy. there will certainly be the perfect home for him out there.