My 340 is actually the Sears variant like yours. I didn't try a reciever sight (though I should have), but there is a seller on Ebay with machined aluminum scope mounts that bolt right on, are much more solid and look better than the stamped metal Weaver ones and have a rail system on top so you use ordinary Weaver type mounts and you can get a lot more fore and afet scope movement with them than the standard stamped sheet metal ones. If I can find it again, I'll post a link.
I really like mine. That little rifle that way I have it set up is a nice woods gun, very handy and pleasant to carry and shoot.