you will need,engine,loom,gearbox,suspension,driveshafts,exhaust,engine mounts,.....
tbh.i cant be arsed saying the rest..its been asked loads off times and it never gets done.just buy a hgt.
Its all very well just 'fitting', the HGT engine will just fit, as will the coupe turbo engine, the lancia delta engine, Alfa 2ltr TS, tipo 2ltr etc...
ALL would need new wiring looms, ECU ect in the same way the HGT engine does so don't come under the 'easy' category.
The only engine thats easy to fit and make run is the same engine.