Thanks Wayne. Very kind of you. The thickness looked to be about 3/16" I would think at a guess. I can make a bracket and I still have to clean up the base it bolts to on the bumper.
My inlet valve guides have been sleeved thus covering the o ring groove. I have bought a tool to cut the OD of the guide back to .530" to enable me to fit a cup type seal that fits over the guide. A more modern system and allows seals to be renewed without taking off the head.

