I'm going theoretical on this one, as I don't recall seeing a C-55 in person, but I'm thinking that at least the coin entry pieces are the same as the ones on this style of CS-64.
This early C-55 has a taller coin door, as the vending spout is integrated into the door. From the picture
here, it appears a later redesign of the C-55 front separated the vending spout from the coin door, permitting the entire coin door on the later models to be shared with the same style CS-64, assuming the dimensions of the coin door are the same. I'd suspect this is why the early CSS-64 coin doors are made in two sections and bolted together. The C-55 has the coin entry section mounted to the body, the CS-64's have it bolted to the coin door.
I'm thinking the CS-64 sign will work. However, the proof of the pudding is in the eating. Time to get out your tape measure.
