its like any second hand car if its been loved then it will be fine, lets be honest 300.00 with the fact that its been mot'd and has 80.00 of rent in the window would be enough to convince me its a winner.
it depends what your dream is, if you want a good solid reliable car for transport then it is probably just that.
if you really want a gti, unless it insurance or age preventing you then save up and get one.
a 1600 driver with the same components just less power being pushed through it for its life is bound to be in good order
check it, starts, drives no funny noises etc, after that value is just added for desirability, service history and the big one condition.
i just paid 2.5k for a 16v its got all the bits and is standard, im happy cause i think its woth it, if its what you want, in yr budget then i am sure it will be a good starting point, its a good place to learn, parts are cheap and plentiful and its a mk2 what more can you want.