Our house was built in 1940. We bought in 2012. We've replaced the roof, all of the plumbing, new sewer lateral, added a furnace and ductwork (there was none), new electric panel and service, lots of new wiring (we still have some knob and tube in the house but are replacing as we go instead of doing a big rewire), foundation retrofit, hot water heater, tons of termite damage repair .. and that does not include the aesthetic stuff. Walls are plaster and lathe with lead paint.
So basically we've replaced every major system in the house. But there had been no rehabbing before our purchase, so the place you're looking at might be better. Make sure you get a good home inspection and know what you're getting into.