Minis fitted with the 'Clubman style' dash (dials in front of driver) have a black metal blanking plate screwed over the bulkhead hole. This plate includes a large grommet for the wiring loom to pass through and a pressed in indentation to give clearance to the SU Carb. They come up for sale on ebay, sometimes with the wiring loom attached.
Classic Austin Rover Mini Bulkhead Plate
However when a central speedo is fitted it is tight for space behind and a hole is needed for speedo cable. The large hole was omitted from very late Minis and also from the rear bulkhead which were originally used when bodyshells were mounted on a rotating spit for some processes like body dipping at the factory. (see BMC you tube videos)
Edited by mab01uk, 04 December 2018 - 07:31 AM.