Opening Mosler Safes

How to find a key for an Old Mosler safe?
I have an old Mosler safe that I have the combination for and can open the big outside doors but I do not have the key for the inner doors. There is a knob around the key hole that I removed and see the number 298 stamped on the shaft, maybe this is a key number.The number 128568 is stamped on one of the outside handles, I assume this is the s/n. Looks like it uses a flat stamped key like a suit case would use. Anyone know where I could get a key or any info on this safe? THANKS
I have the same type safe, Inner door has a flat type key which is very difficult to (pick),
Locksmith I spoke to said he could drill out brass lock and open door. 65.00 trip charge and 50.00 labor.
Opening Mosler Safes