USA1 wrote:Shouldn't be a problem. It's no different than having three grown men standing in that spot. Also, the safe will more than likely be installed against or near a wall where support is even greater.
Getting it up there without gouging a wall or crushing your finger[s] or toe[s] is the biggest problem. 
Years ago, I bought a gun safe that I didn't want to hassle with putting it upstairs. We finally decided to put it in the dining room. It was a model with double doors and painted black to look like an old bank safe. It amazed me that most people who came over for dinner did not even notice that it was there.