I wouldn't put a snake in a tank above your bp, as i'm sure the other tank will weigh more, unless I misunderstood you.
A male yellow anaconda, will stay around that size.
They don't cost a fortune, I want to say I paid $140-160 shipped. I believe it was $120 for the snake & 40 for shipping.
They're great snakes, look under the anaconda section of the forums, and look at some of my posts that I started.