All Australian minis throughout production used a solid subframe mount, no rubber was ever needed, and never noticed as needed really.
I would think long term on the subframe mounts and remove rubber from the equation for good by going the full metal kit.
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When replacing the rear cones, I think I will drop the radius arms for a bit of a clean up and inspection. Are these items standard consumables that should be replaced, or is it a "not broke, don't fix it" item?
--Radius Roller bearing, Radius Bush, Radius Dust Caps.
A bit of an involved job with a little bit more work than parts replacement. Its easy to remove the radius arm, reasonably easy to replace the needle rollers and bush as well. However the brass bush used one one side of the arm needs to be reamed out. There's a How-To on how to perform this at home but you will need the reamer and extension bar. It may be more suitable to get a pair of exchange radius arms from a mini shop unless you have a yen for garage adventures.
I can't comment on the suspension stuff really. I'm more stock than anything else, but a full alignment would be needed before you went and drove it on the road. It would settle in height once you put the new doughnuts in over the next few months.