The best trick on the RS2000 4x4 is to fit a 2.3 Galaxy engine, it helps to make up for the lack of torque when powering the 4WD system.
The Galaxy engine should bolt to your gearbox I would have thought but I'm not sure on where the starter motor goes on the Mondeo compared to the RS2000 ??
Pic below is a RS2000 4x4 box with a 2.3 Galaxy fitted to it, the Galaxy sump with balancer shafts has been removed and the block machine to take the RS2000 sump.
DON'T use Galaxy cams, inlet or exhaust manifold they are crap, stick to RS2000 parts.
One thing missing in the above pick is the remote oil filter bracket to miss the transfer box, I had to pinch the one from the original RS engine.