Engine conversion in general:
Figure out best position of engine. (very important)
Petroltank might be in the way, so cut or relocate
Use original engine chassis mounts
, or get the grinder/welder?
Make engine mounts
make drive shafts
make exhaust manifold
adapt cooling hoses/pipes (also for interior heating)
adapt excisting electrics. (starter motor, oil pressure light, alternator, reverse light, ignition, etc.)
adapt ECU wiring
adapt clutch operation
adapt gear linkage
The GTI engine is a lovely engine. But it is a lot of work to do a proper conversion. It is not a case of bolting a different engine in. Actualy, if the new engine is bolted in, you have only 5% done. The other 95% are all thing stated above.
Several murena's are lost because people start with a conversion, and stranded.