Personally OP, the fact that your new dog has been used for approx. five years as a pig dog really wouldn't come into it with me - what would come into it is the fact that the dog is unknown, has (from the comments you've given) been raised in an environment that possibly wasn't constructive to it's overall well-being mentally or physically.
Like any dog you bring into your premises at that age, be VERY alert, be extra cautious, take everything one slow step at a time. Get to know the dog one-on-one and see what you think.
Known heaps of pigging dogs. Some I'll bypass cause I sense they'd prolly hunt me, others I'll always stop at for a pat and a chat as they are just gorgeous with beaut temperaments.
All the best, I hope the dog turns out great for you and can now lead a wonderful loving life.