It is highly recommended that you design against buckling for the vertical bit of the gusset plate. Bolting is one of the options which could stablize it again buckling.
I also recommend that you look into the modes of failure in a gusset plate. Hope this might help.
What I can suggest u is to make a hoop at the junction of beam and column so that u can control the shear coming on to column through beam, however it is practically acceptable to have slender columns with wide beamns, as far as the transverse reinforcement of the beam is concern, u can provide...