Biggest problem with trying to increase the front travel are the CV joints themselves. IMHO you'll run out of CV far before you'll be satisfied with the amount of travel...
Other option is to do a SAS which has it's own challenges. There are multiple SAS'd montero's & montero sport's currently out there so there are many you can draw advice from. In fact a good friend of mine who's local is currently in the middle of his Gen I SAS.
For me frankly the IFS travel hasn't been an issue so long as you have traction in back and in most cases, I do. In fact, I do prefer the supple feel off road of an IFS setup over a Solid Axle'd rig like a Jeep, Land Cruiser, or early 4-runner. It's what allows us to cruise comfortably at speed off road as well.
Just something to bear in mind for others considering the swap.