A good friend of mine has his eye on a 1991 FJ80 that still looks and seems to drive like new. But he's worried about the 190K miles that are on it. He's wondering if/when the 4.0 goes out on him, if it's possible to drop in a FZJ80 engine in it without to much mod. He's thinking it would be nice to the added horse power of the 4.5 liter. Anyone have any ideas? ???