so I'm just trying to see if this is possible. what i'm thinking about doing to taking a 86 brat and pull the motor and trany. i've found a donor car that i would take the trany, drive line, rear diff, and cv axles out of so i would have stronger parts to hold up better. i figured i would have to get a drive line made to fit the right length. i want to put a ej20 or ej22 motor into it to give it some go. the donor car is a mid 90's legacy. i just want to try and find out what i need to do before i get to deep into this build and get stuck. anything will help out. 

From what I remember on reading for a swap of this nature...

 

The ECU, engine harness cut down and excess removed, build a cross member for the tranny. hybrid axles as neither the Brat or the Lego axles will work, custom shift linkage and driveline. I believe the rear diff may be a bolt in, but don't remember for sure.