LogFAQs > #904652024

The N64 did have some good compressing ratio if they really wanted to.
Resident Evil 2 on PS1 was on 2 discs and the N64 version had the full game with more items, running at a higher resolution and using higher quality audio. The downside was that the FMVs were more compressed, but the difference was not that huge.

That said, Final Fantasy VII had too many pre-rendered backgrounds and FMVs to make it possible, even if they compressed the hell out of them.
But if they rendered the maps with the game engine, think like the world map, and made most movies in the game engine, then it is theoretically possible that we could have got pretty much the same game as the PS1 version.

So the question is, do you mean a 1:1 copy from the PS1 version? No.
Or do you mean with graphical changes that still delivered the same story and gameplay? Possible yes.