Try going for an earlier MPEFI EA donk, should be cheaper by far and your will probably find one thats done lowish k's on a reco for around $500 or so. Crossmember doesn't need to be changed, just get the correct engine mounts - check the XG ute/pano setup.
No need for a new trans neither - bellhousing is different I think and maybe the input shaft but thats easily checked via a wrecker.
Wiring harness/computer stuff should be easy to get hold of, EA's used a seperate computer for auto trans and no BEM with Smartlock stuff. only thing I can think of that may need some sorting is the P/S sensor, check current fuel pump pressure, shouldn't be a hard conversion.
A lightweight XF with 139kw's under the bonnet will kick some bottom :)