Bloods get pretty big... I think 7ft and have hugh girth (i might be off on the length)
I wouldn't be buy a from a petstore... you're better off finding a breeder, you'll pay less.
they were both wild rescued and neither have been a problem
I wouldn't follow this logic. While some WC snakes can adapt to captivity, you'll still need to spend lots on wormers and vet fees, and it isn't really fair to the snake to be removed from the big outdoors they are used to and be placed into a tiny tank.
Boas get pretty big, you might want to stick with a BP. But try and find a breeder to get it from.