Rover, as a noob dev, I have a few technical questions -
1. When they provided the assets, what format did they provide? This could be interesting, because I'm not sure how the palette requirements/sprite size requirement for the SNES version match up with the PC Engine. Also, we are still struggling with sounds and music. I imagine that it is fairly difficult to port these from one platform to another.
2. Did they provide any code, or is this all scratch built? Does this mean every "port" of Sydney Hunter is really going to be its own game with its own feel? Generally, it seems that unless there are really tight specifics, such as the code on how jumping works, control in the air works, and etc, each game will have totally different control. They may end up feeling like totally different games at that point.
3. How much time is this going to take you? I think the answer to 2 changes this massively, if you are rewriting a game from scratch.