I am in a similar position, but wondering if I should keep my rigs or sell it all. Anyway, here are my thoughts:
Take the clutch out of the equation. If you need one, you need one, W56 or 151. If you are planning to run the turbo flywheel and turbo clutch, then add it back in, that was not in your note.
Are you ever going to ask for more power than the 22RE? 4.3, 7M, 3RZ, etc? If it is possible, then stay with the R151, and eventually buy a second 23-spline case. The W56 will be challenged with 35" crawlers, more power, and 5th gear highway use. My opinion only, other will have theirs.
Also, along those lines, what is your intended use for this? How hardcore do you intend to get? The more intense your journey, the stronger the tranny should be. And don't forget the lower 1st gear...