A Volvo collector/purist will place more value on a car that is original, intact and unmolested.

A person who is looking for a daily driver will place more value on a car that has been maintained in this condition from day one, but not necessarily restored. A car that is completely original has probably sat for a long time and will probably require an extensive 'going over' before it can be driven reliably.

In the market for 'classic Volvos', there are more prospective buyers who fall into the latter category - looking for a maintained daily driver. That being the case, if you friend's car has been sitting for a long time and/or needs work to get it back on the road, then it is probably worth slightly less than the 'going price' for a '64 122S despite the fact that it is all original.

A running 122 is in substantially "good" condition but needs some mechanical work is probably worth $2,000-$2,500. A "mint" car, or one that has been reconditioned for use as a daily driver, might fetch $5,000 but that is really the upper end of the market (although you do occasionally see folks advertising "fully restored" examples for $10-$12K, they are trying to recoup the expense of parts + labor). It might be worth it to have some work done to your friend's car before advertising it for sale.