The loyale can fit any ej engine physically with no modification. You will need the engine control parts of the wiring harness and ecu of the engine of your choice.
If you want to keep the 4wd trans, you need an adapter plate, otherwise you can use the ej trans, but that will make your car awd and has to match the rear diff ratio. Plus the axle spline count is probably different, so you'll need to modify the axles or do the five lug swap. And you will need a custom length driveshaft and possibly light modifications to the crossmember.
I have a 95 ej22 in my 86gl and it's perfect for her. I think a turbo might be a bit much. She burns out through second and chirps 3rd haha! I used the adapter plate to keep the dual range.
You're talking about 2.0 so you have a rx or sti swap planned? Awesome! Lol
And to answer your question, no it wasn't a lot of trouble, and I learned efi as I went! I would say the radiators goofy inlet was the most troublesome, so overall easy! I never even hooked up the vss, lol!
Have fun wrenching!