I fitted Miler split bushes to Lil Blue when I owned it. I can't say I was impressed actually. OK really easy t fit as they're split. But my first set wore very quickly. As the leading / trailing arms on an 80 are basically the same design, I'd guess that the Milner ones were split for this vehicle too. Given the flexing that an 80 does I could see it eating the Milner bushes for breakfast. I still have my factory ones in that moment and they're fine after all these years. But if I had to swap them, I'd look at the Pedders ones I think. I am sure that do a genuine rubber replacement. In truth I am not sure that the bush is the limiting factor on the 80. When you look at the eye and socket design, the arms can only twist so far. I have toyed with the idea of modifying mine and on the chassis end going with more of a rose joint - spigot arrangement like a LR has. It's no wionder LRs flex up so well, they're not inhibited by the physical nature of the attachment point.
Chris