After years of stripping and rebuilding remote boxes, I always understood that 4 synchro bronze selector forks were shorter than Mk1 were.
I wondered why, in fact recently I cut down some new Mk1 forks to Mk2 size for a Mk2 box, to comply with Mini folklore.

FF to today, I stripped my spare Mk2 S box and discovered it had a Mk1 selector fork in it, uncut.
It doesn't touch the case, so I wonder why BMC shortened them?
As the more wrap they have on the synchro sleeve, the better for shifting.

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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.