e_collop: I did just the opposite on a Winchester 444 and had to fill in the slots cuts for the magazine tube retaining wedge and add a new screw hole. I'm not certain if the Marlins are set up the same way - sometimes you need a slot cut into the bottom of the barrel to allow for passage of the barrel band screw between the barrel and the tube magazine. You might also need a hole drilled and threaded for the screw that runs up through the magazine plug and into the barrrel.
I have no doubt you can get all the parts you need right from Marlin but I would check with your gunsmith first to see what work is involved, first, and then decide. Depending on how good your gunsmith is, you may wish to fire-lapp your barrel afterwards to reduce the possible effects of machining work on your barrel. HTH. Mikey.
