i have a question that hopefully someone can answer

Will be purchasing a late 80's 70 series landcruiser SX5 with coil sprung axles, I want to upgrade the axles to 80 series for the extra width and strength im led to believe.
Has anyone here performed this conversion and know how much is involved? My main concern is the steering side of it, not to fussed about cutting and relocating spring platforms etc.
Any advice would be much apprecated
Cheers
Grant