maddmatt,
I'll give it a shot. I think the SM 465 will bolt right in place of the SM 420 however, with the divorced set up you will have to have a new drive shaft made to go between the trans and transfer case, the front shaft will have to be lengthened and the rear shortened. You will have to pay particular attention to driveline angles as you can develop some major driveline vibrations. Make sure the drive shafts are reworked by a reputable shop that specializes in drivelines. They should be able balance the shafts, tell you how to install them in phase and give you an idea of the correct driveline angles.
The biggest concern is the fact you have a short wheelbase vehicle which may not have adequate length to use the divorced set up and achieve correct driveline angles, especially if you intend to add a lift kit.
This is how the oldie 4x4s were built so have a look at some to see what is involved. I have a 1942 Chevy, 1.5 ton Army truck (pictures in the gallery) with the divorced set up; the wheelbase is fairly long and even then the drive shaft between the trans and transfer case is extremely short.
Good luck.
