Mounting ltz400 spindles/hubs on the front of the zilla isn't too complicated and definitely gives you more wheel options with 4/144 vs. 4/166.  Easiest way is to run lt500 upper ball joints on lower and upper mounts with a 5/8 thru 3/4 in spacer sleeve between ball joint and upper a-arm.  This will require some fairly easy but tedious fab work with a dremel and correct your camber.  Also needed are  two 14x1.5mm 2.5in length grade 8 or higher bolts to allow lengthening of upper ball joints when installed.  Use of the 400 spindles will also require you to flip your tie-rods over also. Then as previously mentioned, the raptor700/yfz450 dual piston caliper is a direct bolt on to these spindles.  I also got the 4/110 durablue rear hubs made for the lt500 to complete a matched modern hub pattern set.