I,m doing the same job on my mates 90, you have to use the same transfer box mount on the drivers side,i had to redrill the chassis on the n/s .
Try and get a doner that has the diff lock transfer box, that way you will have everything you need,
the exhaust is a bit tricky, if you use the rangie front down pipes and Y piece , you will need to fit the rangie cross member and modify it to take 2 bolts at the bottom on both sides
HTH woody