Can you put up a picture of the gusset & crack.
I hate bronze as it's a bugger to get rid of to weld properly but it does have it's benefits.
If you have a plate with a crack in it then laying bronze over the top won't give any strength and it will crack again. Bronze works best if the plates overlap each other or the joint can gain strength from different directions, eg tube to tube to form a "tee" joint.
First choice, TIG
2nd, Mig, if you can set up for thin material.
3rd, oxy fusion welding
4th, arc, again only if you can handle it with thin material.