It'll be fine with an OME kit, but you will be highly disappointed in capability. Got a buddy with a 88-89 4runner, 4.88s, rear locker, dual cases, 33x10.5 KM2s & he struggles to keep up with my SFA, no lockers, and 32x11.5 rig..
I'm willing to drive my SFA rig hundreds of miles to wheel.. It's not anymore uncomfortable than an old IFS rig.
The biggest reason Im saying SAS is because you'll have to really be pushing your IFS rig hard to run the trails you wanna run and that is more likely to break down than an overbuilt SAS rig.. I feel the SAS would be more reliable because it wouldn't have to be pushed as hard.
Now if you were gonna stay on fire service roads, then IFS all day... But you've already mentioned single black Diamond trails
I think that depends on your terrain.
That is probably true in Alabama, but here in the west, lockers and gears make all the difference. I had the reverse experience as the guy above: Guys with no lockers and big tires could not drive up what I could. Now, out here, we have all the traction we could ever want, even in the wet. I know in other places, Alabama i'm guessing is one, that you NEED all 4 tires on the ground, as the mud is slick and even with all 4 wheels driving, you cannot keep up if you don't have all 4 connecting the ground.
Stock IFS, 33x9.50's all terrains, ARB's front and rear, dual cases with 4.7s in the back, 4.88's in the diff.
Drove this unassisted.
The only time that truck held me back was due to my aversion to body damage: Essentially, I wasn't willing to drive up something because of the assurance of body damage. The truck could have driven it fine.
That said, I don't know what black diamond trails compare to out here, so I'm not sure if you are considering much harder terrain. As I said, it all depends on your terrain.
Wheeling IFS hard means you MUST have a light foot. That may also not be possible where you are at, so totally understand the need for beefier components, which a SAS would get you.
Anyway, sweet truck, and looking forward to the build!