Rangie Spares/Les Richmond Automotive do a taper shim/kicker that slips between the triangular bracket and chassis plate to 'correct' the angle of the bush.
I've also found that Fulcrum Suspensions, the manufacturer of Super Pro bushes here in Oz make a superior designed bush that will totally outlast the OE one. Yes it is urethane, but it is the only spot I will use a poly type bush, and the Super Pro one uses heavier thickness plates (so the don't bow/bend with the load) and use a circumferal groove and chamfers around the OD of the bush to allow it to flex/articulate (more than the OE bush) without stressing the bush material, yet the actual compression characteristics are better than OE, reducing the dreaded rear steer.
They've been in my 130 for around 80,000km now.
If you really want to make some cranked arms, there are some good threads on the Outerlimits Rover forum, generally using 40mmx20mm DOM tube.