Before you do ANYTHING, close the action and, with the help of a small light source, check the bolt guide rails behind the bolt on the receiver.. If you notice a series of about 6 square indentations on those rails, you should immediately do NOTHING but re-sell that rifle and move on.
This.
Or this by Ahlman's Rifle Work
http://www.ahlmans.com/rifle-work.htmlConvert Rem. 742 to pump action ...$249.00