Hey, the issues you will have is
-Swapping the throttle body from drive-by-wire to cable, i just got a falcon throttle body from a wreckers and welded up some ports and machined it a lil
- Exhaust, this can either be a cheap quappy job or a decent waste your money adventure
- Radiator and FANS!!, depending on what it is going into, the radiator you are more likely to fit in there is the radiator from a BH5 GT30/BE5 RS30. Finding fans is a prick becasue of the lack of room, i ended up using a STi A/C fan and running it backwards (harder than it sounds as it is a variable speed one)
- ECU, you pretty much have to go aftermarket, and your only options there are a Link G4 Extreame or a Motec M800. Either way its goign to hurt your bank account
After i finished mine (which i got my motor for $1400, which was a steal) it cost me $7k
If you have any questions just pester me, iv got no qualms