Huh, TIL that the NES Contra is a massively truncated port of a much longer and more varied MSX version.
The MSX version has no scrolling (as is the case with most MSX titles) and chunkier movement though so it looks like it'd be an overall less fun game to play.
You'd likely need to do the same for the un-ported stuff. Add a little more bulk to the individual levels because they're quite short on their own. MSX limitations with scrolling and stuff I guess.