I think the only difference between Canadian vs. US models is the speedometer of course (kph vs. mph) and daytime running lights. I don't see how you could have trouble importing the car into California in regards to emissions, since I ASSUME that a Texas Mercedes, is the same as a New York Mercedes, is the same as a California Mercedes, and is probably the same as any Mercedes from Canada other than the two little quirks I mentioned above.
I also did notice that in W124's, Canadian M-B's have a button for snow chains, while American M-B's don't seem to have it.
1995 Mercedes-Benz E420 (W124 - Black Pearl/Black)