[orient81]

I'm thinking of buying a female royal.

Would I be able to keep her safely in the same tank as my 3 year old male?

 

[markhill]

Possibly, but only if you got a female that is at least 3 years old and weighs 1500 grams, minimum(breeding size, minimum) or your female could get gravid too young.
There are other reasons not to house snakes together, I think theres a sticky at the top of the snake section.