There are two phillips head screws that you can see on the front of the cluster around the top. There are also four studs (two on each side) of the back of the instrument cluster. You will need to remove the nuts from these studs. Of course the wiring will have to be disconnected as well. Be sure to mark everything. Now for the trickiest part. To get the cluster out you will need to lower the steering column. There is a bracket that is held in place by two large screws with relative large phillips head bolts. These are usually very tight and you will need some leverage to get them loose. The problem is the screw driver is hard to hold in place and keep enough upward force to prevent slipping. Use a ratchet with a screw driver type attachment if you can. If you remove these I suggest you replace them with bolts that have an allen head.
In my quest, I found a recycling site in Cal. that had a bezel from a ’55 for sale…including pictures of front and back! Once I saw the back side, I noticed the studs.
Your description is spot-on!
I was concerned there might be no repairing damage I would do without expert advice.