Not sure if I have this right, but I have four bolts lableled batt tray.
Two are 5/16 by about 1/2 inch long with large 1.125 inch captured washers. I THINK those are for the bottom.
Two are 5/16 by about 3/4 inch long, pointed, with smaller 3/4 inch captured washers. looks to be the same as the headlight bucket bolts.
Not sure about the clamp bolt. I know it is 5/16 and know it has a captured washer, but not sure of the length.