The water jacket flush set up.
 

I finally have the pics up for when dad and I flushed out the water jacket. We made a blocking gasket to go under the water jacket where the thermostat would have sat and we used plastic and hose clamps to shut off all the other outlets as best we could.

We have some water leakage out of those but not enough to prevent the water jacket being flushed out.

Dad rigged up a device that allowed the use of the water hose to run water through and out the water jacket, flushing out any gunk. He could also put compressed air to it but we didn't go that far. I didn't have much gunk.