If Brent suggests 4.9-1 tcase and eventually 4.625 ring an pinions, then it's probably good advice for those tires. His opinion is valued and he is an excellent vendor.
The philosophy behind tcase gearing and dif gearing is much-debated - but I can tell you this from doing a ring and pinion regear and what I have read about tcase regearing:
Tcase regearing is a much simpler, less labor-intrensive process.
There is a wide range of ratios available with tcase regearing - more than with ring and pinion options.
Simple is good. more options is good.
There is, however, something to be said about gearing the dif to take the load off the drivetrain...
...and the debate rages on...
You can bolt in the front (tracker) pot into the samurai with no mods at all. IT's better to install the gears into the samurai pot due to the strength.
The tracker front pot will not oil itself properly so if you drive at high speed and for long distances with the hubs locked it will not last very long. We've run alot like this and they are ok as long as you not lock the hubs and drive fast.
You can take the front tracker pot and change the side gears and run them into the samurai but I'd never do it and strongly advise against it....the no oil problem is going to make itself apparent very fast and you'll see how much they are weaker.
IF you can weld and grind you can put in the tracker rear in the samurai but you'll need to fabricate a "hybrid". You'll need the outer tubes of the samurai rear housing and the middle section of the tracker rear. Install the tracker gears into the middle section and install the axles. Take a measurement so you make sure the tubes are the right length. Make sure to slide out the axle a little bit. You don't want them in all the way, otherwise it's hard on bearings and parts.
I've built a jig to put these together but we've done many "freehand" and had no problems. Tack it all together and take measurements....remembere to measure twice cut/weld once. I always ask someone to take a look before I weld it up. I have a tendency to work too fast.
So done right and strong you'll install the front gears into the samurai pot, for the back you're going to weld up a hybrid and use the tracker rears and these are tough as hell. You can weld these up and they will hold and take alot of abuse.
I'd always do the gears first but it's because I know how to and I find it cheaper. The only negative is that the low is always there. I was running 512's in my 413K with 31's and was in 5th gear and could cruise around town. I could go 90-100km/h but it was pushing it hard.
My friends are all running 512's and they have 33's. They've never complained about it and they all have the 5th gears. We don't run rocks around here. Hills, washouts and trails with some mud. Actually there is plenty of mud but I hate paying for the repairs that mud will bring on.
Around here we pay anywhere from $75 to $125 for tracker pots, tracker complete rears are cheap...$50. The guy that does the install for the fronts charges $75 plus parts if need be....bearings, seals or crush sleeve. Always change the crush sleeve when you take them apart and if you don't know what you are doing for gear install then pay someone....it's not worth the money to loose your gears and remember to make sure the oil is in there and good.