[Eatoniashoprat]

Things you need to do this conversion:

-adaptor plate/flywheel
-transaxle to handle the torque
-radiator with electric fans mounted up front w/ adequate ducting
-if its a turbo you need to mount the intercooler some where or go with an air to water unit and use an electric water pump

kennedy engineering makes a kit with adaptor plate and flywheel that a lot of people use

doing a non-turbo would be much easier, an EJ22 non turbo and is between 135-140 hp, and EJ25 non turbo is around 160-170, a EJ20 turbo is between 230-270, and an EJ25 turbo (newer STi engine) is around the 300hp mark. I would suggest the EJ22 because they are widely available and are they least expensive option. all the engines have the same bellhousing so are interchangeable. THe other difficult thing about this swap is the wiring, a lot of the wiring harness can be removed. another option that people do in some dune buggies is ditch the efi and make a mount on the intake for a 4-barrel carb.. on an EJ22 this will put you at around 120hp if its tuned decently.
Not sure if thats completely what you were looking for but hope it helps