I wasn't aware that Marlin made any MR-7's with any other loading option than a clip on a hinged plate.
Just what would the advantages be of having to load it from the top? It would also mean cycling the rounds through the action to unload it, unloading from the bottom is one of the strong points of the system as manufactured. Unless you mean to have the clip lock into place from the bottom.
Either one sounds too complicated to me.
Marlin won't give any advice which is away from the design. Liability keeps it that way.