If you can change the gasket on the Mini, the Cinq will give you few
problems.  I changed the gasket recently on a FIRE 55S punto and found
it to be a job that can be done in 2 hours.  If you have a similar
FIRE then read on.

Make sure you secure the engine at TDC in cylinder 1 - check the
Haynes manual and the crank pully.  Remove the timing belt, drain the
water and disconect both sets of manifolds.  Undo the head bolts in
the reverse order and off it comes. The most difficult part is
refitting the timing belt and possibly the exhaust manifold bolts
(rusty).  A new head gasket is about £7 from a motor factors.  If the
engine is losing water, then it is almost certain to be a pit linking
the water channels to the cylinder caused by corrosion.  It is
remarkable how small this can be and yet cause so much water loss.
Pitting the size of a grain of rice and about 0.5 mm deep will drain
an engine in about 2 weeks.  Have the head skimmed - about £25 in a
engineering firm.

The crank pulley will come off easily as it is held by 4 bolts - no
large Titanic bolt that needs an airgun to shift it.