I couldn't find much for the lt230 side to go 1350 or larger. Only that the ford 9" splines are the same, and to do as Mongo has. There is dana60 to LR, lt230 to 1310 cv. Looks more like we must do as they had to in the past, make our own.
I am thinking of just going 1350 all around. Using ford flanges. But my other thought was Toyota stuff. My buggy was on 4D's, Lincoln lockers, 10:1 t-case, and never had a problem with the toy junk. That was with all used shafts, cut down, homemade. They have the toy flanges for my axles, and 9". But I'm going to investigate the ford flanges more first. I want as much off the parts store shelf stuff as I can, I learned the hard way about "different" and "custom".