a good GTI will stomp those miles out without a worry. but i wouls suggest if it has to be ultamtaly relaibale buy a run out speck car if you can and then some preventive matance. i would be very tempeted to put LPG on it as the engines take it well ok you loose a bit of power so get a 16v to make up for it.
would suggest going over the car like hawk tho and rplace any mecanical parts that look like there about to go. top on my list would be wishbones, metal water pipe, oil cooler , water pipe from pump to metal water pipe, rad, thin braded pipe from rad to top bottel, top bottel cap ,heataer matrix (if not had one / feeling keen) water pump if looking makyey and a new set of belts, plkugs and leads. that wouodl be the most common reasons for seeing a gti stranded removed.
may look like thats all colling system stuff nearly, but it seems that a lot of parts ve used in the cooling system were good for about 20 yrs hence atm it becomeing more common to have cooling issues at least there easy to fix