from the threads ive read putting in the engine itself isnt particularly hard, a bit of fabrication for mounts is required. the hard part comes with the wiring. if you use stand alone management its a bit easier and qpeng do a complete plug n play kit. if you use original ecu then you have the immobiliser issues which can be a nightmare. with stand alone you are going to have costs in mapping the engine/ rolling road time. other problems arise if your going to use a cable change gearbox, but there are solutions out there you just have to search.
have a look on the mk1oc website there's afew peeps done this conversion
