On the prewar conventional bracket and the postwar 53-56 factory brackets the thermostat housing bolts were part of the mounting.
On the Clipper engine photo in post 12 there appears to be two extra bolts in the head next to the thermostat housing. I suspect the bracket West posted below the engine photo might have used those bolts and an additional piece or two to support the other end rather than share the housing bolts. If the extra bolts were used then possibly the bracket might have overlapped the thermostat housing but can't say for sure. There is not enough of the flat bracket to say exactly how it mounts and not enough seen of the bracket in the Detroit library photo for an answer there either.