Wow! That actually sounds hopefull in terms of length at least, unfortunately it sounds like the diameter would be a problem although possibly not insurmountable, may be possible to offset the push-rod one brake or clutch.
Do you have any idea what the bore size of the master-cylinder is?
The only think whch sounds a bit worrying is that presumably the master cylinder must be very short (185mm overall indicates cylinder must only be about 100mm or so maximum) I wonder if this would have enough stroke to operate the Jaguar calipers and not bottom out. But obviously it works in a Rover 25 so presumably could be made to work here.
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