The track of the axle is wider, so you'll have the wheels sticking out. Not a problem - but you'll need eyebrows.
If you modify the chassis around the suspension mounts you'll need to check to see if you need an SVA. I think they changed the regs and that 'any' change to the suspension now requires an SVA.
As an alternative, you could find some Stage 1 axles (rocking horse poo - I know).