It's pretty much a one off, so there really isn't a standard. If it were me, I'd just assume a complete replacement of the transom and consider the bracket as a freebie that I'd start from scratch and build/reinforce around. I'd want the security of knowing it had been done correctly, the old I/O holes sealed up, bracket mounted appropriately and with the correct hardware and sealant, and any additional support issues accounted for. I'd also look closely at any hull stiffener considerations and potential cracks as we have witnessed many on this forum run into concerns with some of these larger hulls.
