If the exhaust and turbo are intact on the '90 motor, you can use them for faster spoolup (or it might just be in better condition) - the cooling hoses will be a match. Use everything on the intake side, including the manifold, from the '88. The '90 uses LH 2.4 - different injectors, cold start valve not used on '88, idle air motor and coolant sensor need to stay with the car. In short...do it as though you are installing a bare long block from a rebuilder.

The other bolt-on crap doesn't matter. Replace worn accessory bushings while you have the goodies unbolted.

One more thought before you start this. >>IF<< your car does not have an updated wiring harness manufactured after 1989, this sure would be the time to replace it since it will need to be mostly disconnected for an engine swap.