ive been to see a mk2 golf gti 16v,its oak green

and it seems to run very well even though it has clocked up 158,000 !! should i be worried about this,the brakes seem good and it doesnt smoke.There are things wrong though which will determine whether i am to buy the car, firstly there is leak in at the sunroof,its a steel sunroof and when it is closed the seal doesnt sit write so im pretty sure its that.What do you think?
Seconly there is a leak in the boot,not too bad but enough to cause probs! it may be leaking from the cluster light but it would need sorting.
Thirdly the electric windows dont work at the back,it may be the motors or something like that.Also the front windows are very slow.
The car has mot but no tax and im thinking of paying ?1350,its in good condition and has bbs alloys which are mint.
Should i buy or walkaway?
Does anyone have any advice on the problems above?