Feb 24 (Reuters) - NEW YORK (Standard & Poor's) Feb. 24, 2012--Standard & Poor's Ratings Services today assigned New York City-based entertainment company CBS Corp.'s proposed issuance of 10-year senior unsecured notes its 'BBB' issue-level rating. CBS plans to use the net proceeds to repurchase or repay outstanding debt, including the redemption of some or all of its $700 million 6.75% senior notes due 2056, with the remaining proceeds, if any, going to general corporate purpose