I wouldnt say it would be horrible overkill and I'd rather have a little too much GPU than too little. For example the 760 might get you ultra in some games that a 750Ti could only manage high in.
Do modern games even play at 1366x768? I would honestly get a new monitor before upgrading. 1080 is the current standard and I wouldn't build a rig around an old one.
Do modern games even play at 1366x768? I would honestly get a new monitor before upgrading. 1080 is the current standard and I wouldn't build a rig around an old one.