IFS Gear Swap

I've got a '94 Sierra GT 4x4. The previous owner installed a 3" body lift , a 4" suspension lift and 35" tires. But, they didn't do the gear swap to match the tires. I plan on installing 4:56 gears. I know that the rear-end isn't that hard to do. But, as I was checking out the front end I couldn't figure out where to start at. Does the whole front end have to come out? Half shafts and all? or is there an easier way that I'm not seeing? I did a forums search, but couldn't find any info on this. So, forgive me if it's out there.

I guess no one has ever done a 4x4's front gear swap on an truck with IFS themselves. Has anyone taken thier truck to a mechanic to have this done? How much did it cost to have it done? Did the mechanic give you any idea on what was involved in changing the ring and pinion in the front end? I'm sorry to keep pestering you guys, I'm just checking to see if anyone knows about this.