I don't think swapping the chips will help

If he is only able to see 1 Meg of the ROM then it probably means the hardware is only capable of banking in a maximum of 1 Meg at once.

The rom should be 4 Meg, of this I am *100%* sure.

I can create a fake ROM, with comes to 4meg in size, using the existing dumps of other games, and it runs fine in my emu (apart from Castle of Illusion, where the Sega logo code seems to break it)  Of course a fake rom isn't the solution, the real dump would have pirate versions of all the games with the logos removed etc.  the fake dump is just proof of concept.