Dave:
The Kubota pins have a hole in one end and the other end has a recessed grease fitting. There is no flange; the pin is 1" OD all the way, so it will go in or come out either way.
The elegant solution would be to make a flange out of say 1/4" X 1 1/2" bar, drill a 1" hole, stick the pinl through it, and tack weld the flange to end of the pin. I doubt the minimum heat required just to tack the flange to the pin would seriously soften the pin bearing surface, which is 1 1/2" or so away (of stick the pin body in water to keep it cool), and I suspect the pin is only surface hardened, so the overall strength would not be compromised.
The less elegant solution would be to take a 1/4" rod, weld a washer axial off one end of the rod that your flange retaining bolt will pass through, and put the rod through the hole in the pivot pin and secure it with the existing flange retaining bolt. If the rod sticks out of the pin only an inch or so to reach the retaining bolt, the twisting force on the pin probably will not bend the rod.
I have the length of the pin at home. Want me to send it to you this evening?