i work at a vw repair shop so i know what im talking about. First of all that car can handle a bit of milage but it all matters on how it has been maintained.
about the compression...the main thing to test is if all the cylinders read within about 10 of eachother. im not sure what range they will be in just make sure they are pretty close.
Then with maintanance the thing to do is to check the belts and fluids or even better is to take it and get a routine tune up and ask for a list of any other things wrong with the car...do what you can by yourself..then have them do the rest...if you can afford it
Sorry but i dont really know of any upgrades for a corrodo
I hope i was helpfull, good luck with the car.
