Keep in mind if you do find one that H&R will NOT fit barrels to the the Marlin receivers, even tho they built them. I paid a little extra for a .28 gauge barrel off GBO classifieds to put on my Marlin 200 receiver, only to have a local gunsmith butcher the fitting process...
...that project is on hold. The Marlin receiver serial numbers start with KM### if you ever find one you're not sure of...Scott B.
My "repurposed" Marlin 200, a .410 slug gun: