Have you tried mating it up to the engine? Most of the times smaller engines are the same block with either a larger/longer/smaller bore and stroke so all ancillaries fit. At a guess I'd say yes it's going to fit unless theres a major engine change at your year. The gasket I wouldn't reuse. Get a tube of Hylomar blue.
I cant remember off the top of my head, but is the timing belt tooth profile the same 1.0 <> 1.2 ? If not the pully on the pump will be wrong and im not sure if they can be changed.
A new pump will have a new gasket?! DO NOT use an old one. They are only cheap £25-30, and do the cam belt at the same time if your doing the water pump.
all water pumps are the same apart from some of the early 1.0 ones have square teeth and later have rounded but just check what teeth shape you have on before you buy one.
Arnold dont be so tight and get a new one. Even if one was 6 months old I would be hesitant to re-use it. Good point bob about the difference in belt pullies.
why? its a balance between the hassle of having to for any random reason replace it soon after you put a new engine in. new water pump and belt, and everything is guaranteed to be fine!