Sorry bout that. I know what you mean.
The 270 WSM would fill that " gap" nicely. Actually that cartridge would be capeable of taking all of the hooved game that this country has to offer. I mean everything except for moose. You would still need the 300 WM for moose.

You could still go to the other end of the spectrum and look at a lever action big bore for the deep Maine woods. You know, a gun that is short enough and fast handling enough so that it allows you to hunt in the thick cover where that long bolt action 243 and 300 are just too much of a hinderance when you are trying to negotiate an undergrowth thicket quietly. Those long bolt actions just seem to catch on every branch in the woods.