If it’s about the 16*9 look, I’d do following: If you still have the project with all single shots/clips on the TL use that one, otherwise make a new project, drop the whole movie into a new TL (which is still a 4*3 Aspect Ration), and then slice it up again into the individual shots.
Now, drop on each clip a MATTE Video Filter, set it to the Aspect Ration you want and move the clip in between the Black Bars with the “Offset” function, till the framing is to your liking.
Greetz,
Sascha