The reason there is not a 1.5:1 t-case option like there is with the Samurai is the fact that in high range on the samurai you still go through a set of gears. That is why the Samurai t-case has off-set rear output shafts.
The only option is to run with the Samurai T-case swap, as 95tracker mentioned, or swap over to something more exotic.
The undertaker is a nice option if you have room for it, it also gives you the reduction in low range as well as high.
One option is to switch to a 9" or Toyota rear end with 5.88's in it then swap your front gears out for a set of 5.88's so you can keep the stock front suspension setup.