The knuckles are a common cut point because you can just cut the factory weld, and the knuckle balls have a smaller ID portion that slides right into the axle tube. This allows for easy positioning and a factory-like end product. Then you cut and re-mount the spring perches and you can adjust your caster angle and pinion angle at the same time. If you don't need to adjust your caster angle, maybe rotating the center section up is an option, but you'll have to sleeve it internally or externally and there will be an obvious weld somewhere. ZUK has sort of done what you're talking about. Check him out on YotaTech, I don't think he's here as much or at all. He welded a LC 9.5 center into the middle of a Tacoma rear housing.
