James,
Could be a UK rack, Mk2 or later. Steering arms used are different angle to all Oz arms, and the rack gives sharper turning circle and more turns lock to lock. See how many turns it is- 2.25 approx is Oz (Mk1 type) rack, 2.7 is UK Mk2 & later.
If you mix these racks & arms the geometry is out, but nobody seems to give a rat's... maybe they don't know.
BTW here in Oz there are 2 arms, the early 850 etc and the thick Cooper S(& all later). Both have Mk1 geometry. S ones are just `thicker'.
If you really need to use that rack I have 2 only, UK Mk2 arms here..
Don't all trample me in the rush...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.
