I just looked at the pictures, very nice. I'm assuming it's not a Canadian car by the shot of the gas tank.
You may have to drop your steering wheel by undoing the upper and lower bolts. If your bezel is all in one then you will have to pull the light and wiper switches. On my 74 they are released from the back. Undo the screws and gently pry the cluster out. Watch out for the speedo cable.
See if anyone else replies but I think you should be able to get to your bulbs that way. While you have it out you may want to replace the cluster voltage limiter. It's like a $25 to $40 part that you can get at NAPA or National Moparts in Beaverton Ontario. They carry a wide range of parts and are great with technical assisantce too. (No I don't work there)