It's a little more then keeping your factory suspension. For starters, the only thing you will be able to re-use is your springs. And that's if the springs are in very good shape. As for things to change, well, here is a run down starting from the rear.
Spring perches - since your moving the springs over the axle, you'll need someone who can weld the new perches on. This can be tricky on the rear axle since you must get the degree correct so your drive line angle is correct. There is no need to remove the old perches.
Spring wrap - you will need some way to control rear axle spring wrap. When using YJ springs, even with the clamps shut and low HP, your rear axle will wrap. Trust me on this, mine does it.
Rear drive shaft - since the slip yoke is in the tcase of a 231 (which yours is on the border of what tcase you have in an 88) in order to extend your drive shaft, you must move the slip yoke to the drive shaft. This is done with one of the many slip yoke eliminator kits (SYE) available. With the SYE, installed, now you can replace your drive shaft.
Front spring perches - like the rear, you'll need the spring perches welded on. Since they should be parallel, the front axle is a little easier.
Steering correction - There are many avenues to take here. Personally, I like the cross-over route. You can use a drop pitman and the factory style steering, but it's less then adequate for street use like that.