You have to look at it as a package doing an engine swap. There are right and wrong ways to do it. Consider, cooling exhaust, potential driveshaft issues, and adapters into a SBC swap. The most common problem I have seen with the SBC converted Land Cruiser is the stock t-case housing can split under a healthy engine and a a heavy foot. If you wheel that way. To fix that you either swap the whole engine trans and t-case from a chevy, or go aftermarket for the t-case (Advanced Adapters Orion). The pay off of the SBC swap is it has a bit more power, but at a totally different RPM range. It is also a lighter engine, which makes it a little different off-road. I have never driven an SBC converted Land Cruiser, so this is just stuff I have gathered from people who have. Hopefully I have this info close to correct, and I do not intend to bash a SBC converted rig.
Keeping the F/2F. When properly maintained is pretty dead reliable, but not all that powerful, so highways are doable, but at a price. The F/2F is heavy and right over the front axle, so I feel it helps in a climb, but in a steep descent, you know it's there. The torque builds early in the F/2F so off-road, I personally see it as a benefit. The drivetrain behind the F/2F, does have options, as in the non U.S. H41 trans and the Orion t-case for deep trail gearing too.
Search is your friend on this subject, it has been debated to all ends here.
Keeping the F/2F. When properly maintained is pretty dead reliable, but not all that powerful, so highways are doable, but at a price. The F/2F is heavy and right over the front axle, so I feel it helps in a climb, but in a steep descent, you know it's there. The torque builds early in the F/2F so off-road, I personally see it as a benefit. The drivetrain behind the F/2F, does have options, as in the non U.S. H41 trans and the Orion t-case for deep trail gearing too.
Search is your friend on this subject, it has been debated to all ends here.