You intend to rebuild JJ2 (a dazzling feat, since it was made by proffessional programmers, fulltime) but think sprites are stored as animation files inside a game engine instead of as seperate images? (what Doubble Dutch gave you).

I don't intend to be overly harsh, you are essentially doing something out of nicety and have good ambitions, but you should really think things through some more before starting (at the LEAST).