Get the S-Sixteeen mate. I don't know about the mountings for Xsara but this engine does fits ZXs and with the 6 speed manual transmission, just make sure that your braking system is in good condition.
i was told by someone from the forum that he is running standard gaban e3 engine @ 2bar with 450whp...
all the internals are standard, no UPGRADES...
if i'm not mistaken, it only have safc...