I need a 3'0 door for access to my attic stairs in my garage. Since it's within 4' of my woodstove I decided it should be a firedoor. This will firstly make me feel safer and secondly give me the adjustable spring loaded hinges so it never gets left (by some trespasser

) too close to the stove.
I was offered a free hard wood fire door today minus the frame. I'm very familiar with metal fire doors and the adjustable frames but how would I find a proper frame for this door and is it worth the trouble?
tia