Feb 1 (Reuters) - A new bust of Soviet leader Josef Stalin has been unveiled in Volgograd ahead of Wednesday's 80th anniversary of the Red Army's defeat of Nazi invaders in the bloodiest battle of World War Two. The industrial city of Tsaritsyn on the River Volga in southern Russia was renamed in honour of Stalin in 1925, but became Volgograd in 1961, eight years after his death, after his legacy fell out of favour. See here for a complete list of exchanges and delays