I used some round 20mm spring steel cut to length 15 cms about and welded them directly to the bucket bottom, they work very well, the welds do break from time to time, and so need welding back on, but being very small, they do not put much resistance to the bucket when digging.
Called romac, weld on shank, rock tooth and pin $ 20 ea. I need 3, don't know shipping yet, he is out of the shanks wont be in till the 16th nice guy, I told him I custom made the buck based on a kubota bh 90, and he talked me through it