Its a lot of work as the front diff bolts to the engine,
If you have engine issues rather repair it, much cheaper in the long run, and easier for others to assist you. (compared to nissan engine with ford clutch and toyota radiator etc, that type of modification is a pain in the ass, as every time you need assistance with a part..... its a non standard part. )
If you want power try a better cam shaft, and make sure all your driveline components are in good nick as the friction losses could be eating your power.
Regards Ari