That's a good start but I would also change the chainring, cranks, front fork, rear hub and frame.
Yup - free advice is sometimes worth exactly what one pays for it :-)
If you buy it, ride it after checking it out to make sure it is mechanically sound enough to ride safely... Then see if anything needs to be done. New technology is not essential for a safe ride. It depends on what you want... The late Sheldon Brown was known to ride cottered crankset bikes. If he rode them safely then what is the REAL problem??
I am familiar with 28" Atlas and Hero bicycles that are sold and ridden by thousands of people daily as work bikes (delivery) and transportation bicycles. In spite of "old technology", no suspension system, old fashoned brakes, and heavy steel frames and wheel rims, they WORK!!
Tmac - It's the truth. Those old Raleigh 3-speeds with 40 spoke wheels, and all the other non-sport bikes, were quite bombproof, and they were used as daily transportation by millions of people in all kinds of weather for many years, and similar bikes still are. I never did like cottered cranks, though - but a large part of that was never having the proper tools to deal with them. I recall many unhappy hours pounding away on the damned things with a hammer and a chunk of wood, and how they sometimes wobbled...