I bought it in Jogja about a year ago then shipped it on the train to Jakarta a few months ago. In the past year I have done:
New breaks (front and back)
New electrical (EVERY wire has been replaced because I was sick of having electrical problems)
New cables (break, clutch, gears, etc)
I would never go as far as saying that you won't have any problems with it, because with a Vespa from 77 that's a pretty bold statement, but I can say that it is reliable (for a vespa). It's probably not the best scooter to drive to work everyday in macet, but it's a lot of fun, quick, and great to drive on the weekends. I always serviced it at a shop called Vespaholic in Jogjakarta, then in Palmerah since I moved here. Whenever something breaks I have always repaired it the right way, no shortcuts with this one. It has the original headlight and speedometer (which works).
Price is 5.5juta, and the Vespa is in Sudirman/Setiabudi. If you want to come check it out or test drive it just let me know and we can arrange something.
I'll post some photos of it soon!