My '88 (flatnose) Dak with a 5.9 using a Durango pan and sitting on V6 mounts. It's got an LA front on it (timing cover, aluminum water pump, pulleys and alt. brackets). I did have to move the radiator forward a bit ('62 Corvette), only minor sheetmetal trimming and the rad fit like it grew there. An aftermarket radiator was considered, but the Vette unit won out because I already had it.
Mechanical fan, no spacer. I could have saved another inch by using the early iron water pump, but this whole thing was a matter of using what I had. The Magnum pump would have only saved another 1/2" over the iron pump, but I wanted to declutter and get rid of the serpentine system. I also wanted to run a mechanical fuel pump, since the truck was originally a carbureted 4 banger and didn't have the in-tank fuel pump.
Shelbys used the TBI LA engine, but moved the engine back almost 2 inches with custom mounts to get the necessary radiator clearance, and then used a modified B van transmission crossmember. I didn't want to bother with that, since it would have meant relocating the 5 speed shifter hole back and getting a new, shorter driveshaft. Remember, I wanted to do this on the cheap with parts I had laying around.
So I ended up with a 5.9 Magnum, 5 speed 2wd short bed Dak that da** near bolted together with all factory parts (okay, the rad is a GM factory part, but still...) the way Shelby "shoulda" done it.
The only concession I made to Shelby was using GLHS buckets to replace the busted up bench seat...
So, if you're looking to do this with a 4wd Dak, this is how you want to do it, not how Shelby did it- if you move the engine back, then you have to fab your own engine mounts, deal with transmission and transfer case linkages and crossmembers, getting two different driveshafts, and probably messing with your pinion angles on the front and rear diffs.