Fairly sure the front is longer. Surely the smart money would be on holding the thing up on the vehicle and see what fits in the gap?
Re clutch cylinders: The master is the same as used on Series II and IIA vehicles with the bean tin reservoir. The slave the same as various V8 powered models.
If you want a really light clutch then the inch bore brake master from IIA/IIB FC's and non servo 101's will also fit nicely.

