Hello. NEED HELP!!! I have a gun safe locked and no key and cant open it. How can i open?

Hello i guess it is always the law abiding citizens like me that have the problem of opening my safe when locked. HERES THE DEAL-- my great uncle ped away 1 month ago and the family inherited his gun safe(6 feet high and 3 1/2 wide is from the late 70;s era is black powder coated) it has a key and combination lock on it with a turn handle for door. We cannot find no name ,no serial #,no model# or anything on it to identify it,if we could we would get a hold of company and get key and combo,but is not a option since MY UNCLE was the only one who knew where the key was and what the combo was and he is now gone-(A GOOD MAN). We need it open to divide up estate,SO first thing is we called a local locksmith to get a estamate and it would cost us 400.00-600.00 just have him come and open it ,nothing else done for that cost---NO--- WE ARE NOT GOING TO HAVE HIM COME BECAUSE WE ARE NOT GOING TO KEEP SAFE, so is not worth it. QUESTION---can we just drill out combination key hole ourselves and will that be enough to open it and will that release door lock to allow door to open?? Question--If you put a pipe wrench on combination dial and twist it and break free will that open it?? We have no knowledge of what to do to open it and are really lost. PLEASE