You've got several versions of S2 series elise which debuted ca 2000. The first s2's (or standard cars) were first on the scene, with the flat bottom diffuser. Later in 01 or 02 Lotus offered an upgraded version with more options more power called the S2 111S (not to be confused with the S1 111S). This is what all but one of the euro demos that made the rounds in the US were.
The 111R is rest of world, yota powered elise, is like ours with some different components. both have the notched or step bottomed diffuser. A couple things would have to be changed at least to fit the standard s2 diffuser. Of course you have to make the exhaust cutouts, also, you'd have to modify the rear license plate area and/or screens, not sure which would have to be done, I think probably the middle black plate where the licence plate goes would need to be narrower as on the base S2.