not quite that simple... as mentioned before, the tops of the doors are different, which means you would have to extend some standard 1200 door tops, and put them onto coupe doors... Then you'd find the glass will be different, and neither coupe glass or standard sedan glass will fit, and probably not even standard 1200 2 door sedan glass.... You'd have to get custom... I s'pose its not that bad since glass in 1200's is straight!
Don't let me put you off though, go for it