Hi kmrk,
You’re right on there with your ratings: 0.1uF 10%, 275VAC or 300VAC, X2 safety type
See this post for info on the 40/100/56 meaning. They relate to “Climatic Category” specifications, which in this case refer to a temperature rating of -40°C to +100°C, and tolerance of 56 days at 95% humidity at +40°C.
Here’s a link to all of those which look like options. Make note of dimensions for best fit.