How to Narrow an 8 3/4 Rear End

Mine has a 1 3/4" cold rolled shaft, not sure what the spec is, but you'll have to ask speedy or you metal source for one that is straightest. I see the kit from leadmine uses a 1 1/4" bar, I think that's a little on the small side, but could be wrong. I actually just spun out a set to keep for myself and made the plug's out of steel, with a 1 1/2" hole for the bar. I have a couple buddies that want there's done so I figured I'd make my own kit.