i have a 1992-3 rover 216 cabriolet (honda engine) is it the same engine...
 

...as the 1600 prelude of the same year?

I doubt it, rover do not use honda engines, i think tyhat engine was probably fitted later in the cars life, maybe by a hobyist or something, if it is the original engine, i'd be very surprised!, since Rover is owned by BMW