Salvador Allende's economic policies did somewhat prove the viability of socialism. Allende was able to put policies in place that showed that socialism works on some levels of government. Even people in the west not normally known for accepting socialism though his policies help the economics of mid-size to large countries.
Salvador Allende's economic policies proved that socialism works very well, and is one of the best economic ideologies out there. I'm still of the believe that mixing socialism and capitalism is the best way to go, but he did prove the viability of socialism and showed that it works very effectively.
I do not believe Salvador Allende's economic policies proved the viability of socialism. During his time in office he implemented many socialist reform policies, generally involved with the economy but this eventually led to a planned coup d'état that was only staved off by Allende committing suicide. The Christian Democrats were opposed to his socialist ideals. As far as the economy during his time in office, the country experienced quite a bit of inflation. Overall I wouldn't say the policies were in place long enough, nor were they all implemented, so it certainly did not prove socialism viable.
No, they did not prove the viability of socialism. His policies did not work all that well, so did not show that this type of policy can still get a steady growth in the economy. His plans still needed a lot of work before they would be extremely good programs.
Salvador Allende's economic policies were overall a disaster, and to this day the socialist economical model has never been proven viable. The chaos and desperation caused by Allende's inability to manage the economy was a main factor in the coup which toppled him. Only the free market reforms introduced by Augusto Pinochet were able to turn the economy around and thus make Chile into one of the region's most successful countries.