I don't know how correct you want your 74 to look ? Most countries used paint over park . [ Except Romania , North Korea and the Chi-coms] . Russian , Bulgarian , East German and Polish 74's were painted over Zinc Parkerizing when they left the factory . Blueing looks very nice but it would not be durable or look correct on your 74 ? I would suggest finding someone to apply Gunkote over parkerizing. It may cost a little more but it will look correct and be twice as durable. Blueing is nothing more than a semi-controlled form of rust and relies that you keep a thick coat of oil on it if it happens to get wet . Good luck !