I *think* that all you will need is the fan itself. I have fitted the twin fan arrangement to a couple of 205s and a ZX - all had the same twin moulding and it was just a case of fitting the extra fan.
Wiring is slightly more tricky if you want to mimic the original operation - when low speed the fans are run in series (i.e. 2 6V fans) and at high speed in parallel (2 12V fans). The easiest way to do it is keep the low speed operation the same (single fan slow) and then trigger a relay when the original fan kicks in at high speed to power the 'new' fan.
thats a short blade fan cowling so you will need another SMALL BLADE fan motor to go in the other side, other than that it will fit! Best bet is to find a second single fan in a double cowling and fit the whole lot! I prefer to fit two regular fans as they are bigger outright!