ah! design and specs! Well, I have to fess up and admit that it was designed on the fly, on my drive with MIG welder in hand !!
Dictated by the coilover system that I purchased. That is the top and bottom mounting brackets.
The main surgery was removal of the Hydragas turrets completely, the welding of the large top brackets into place (by eye) followed by bracing on either side of the bracket to give it good structural strength.
The bottom mounting had to be modified because I assume that the Mini arms are shorter than the Metro for the bracket to fit over the top swivel nut.
All of this I think you can see in the photos.
As for design - we applied the RJ Mitchell view: if it looks good, it probably is.
My only real concern was potential fouling of the top of the wheel arch going into the engine bay, but it clears that very nicely.
If you can work it out from this short description and the photos you shouldn't have a problem.
