By Naomi O'Leary ROME, March 5 (Reuters) - As cardinals flock to Rome to choose the next pope, two artists have taken the opportunity to stage an exhibition taking aim at the wealth of the Roman Catholic Church and the sex abuse scandals that plagued Pope Benedict. Held in an ancient building where Italy's patron Saint Catherine of Siena died, "The Unspeakable Act" is a life-size model of Benedict in a confessional box, his sumptuous red and cream-coloured robes spread about him.