Oil pan gasket, Shim the wastegate (if turbo), clean oil pressure sender and the clip on OP sender contacts.
Also: MAKE SURE YOU USE THE OIL PRESSURE SENDER FROM YOUR ORIGINAL US MOTOR.
The JDM motors come with an OP switch not a sender. This is because the Japanese car that your JDM motor came out of didn't have an OP gauge, just an idiot light that would come on if there was no oil pressure.
Use plenty of RTV liquid gasket on the pan. I use almost an entire tube when I do oil pans on these engines.
While you've got the oil pan out clean the inside of it really well.
Hope that helped.
-Dave