Well, I found the answer to my question and maybe my problem too.
I started looking for pictures of the 223 block on the Internet. The car photos were of no help but looking at pictures of the F100 truck I noticed they use some sort of front engine mount with a sort of yoke pan that is bolted to the sides of the block at several locations near the front. I found an unused bolt hole a few inches to the right of the oil filter. It took a 3/8" bolt and after a few modifications I was able to bolt the negative cable right to it. First I only had a 1 1/4" bolt which was too long so I cut about a 1/4 " off with a Dremel tool. Then my 18" cable was too short but fortunately I had an old 24" cable lying around and I used that until I can pick up a new one.
As soon as I removed the bolt holding the cable from the thermostat housing water came pouring out. You shouldn't have to go through that just to change a battery cable so moving the cable is a good idea. Next step was to remove the housing, thermostat and old gasket material and install a new gasket and thermostat. Thinking to make things easier I did not remove the upper radiator hose and heater hose from the housing. I installed the new gasket and thermostat, bolted up the housing and when I went to add coolant it leaked like a sieve from the bottom of the housing.
I removed everything and rechecked the gasket surfaces to be sure they were clean and not scored. The only thing that bothered me was that when I was tightening up the old cable bolt it just didn't seem to snug up right which is something I noticed before when I tried to tighten the bolt when the cable was under it. I decided to run the bolts finger tight into the head. No problem with the lower bolt, I could feel it coming through on the inside of the head with my finger. Not so on the upper (old cable) bolt. Apparently rust and scale had built up on the portion of the threads that weren't being used. I used a case hardened bolt to open it up, tightening and loosening it back and forth until it cleared all the way into the head. Put everything back together and once again it leaked at the bottom.
This time I ran my finger down where it was leaking from and I felt something hard and thin there. It was the flange of the thermostat. Apparently it was slipping down out of it's recess in the housing when I was trying to line everything up and bolt it together. Everything looked snug at the top of the housing but it wasn't so at the bottom where you cannot see. OK, this time I remove all the hoses to make things easier to handle and I hold the thermostat in place with my finger inserted through the radiator hose inlet. Still leaked.
I took it apart again and noticed that there is really very little meat around the edges of the water holes in the housing. Years ago when you did work like this you always used a product called Indian Head gasket sealer. Messy, sticky, dried hard like a rock but it worked. Then as we moved into the 70's and 80's came new products that you could use without gaskets and gaskets that you weren't supposed to use sealers on. Well, my bad, I forgot that this is a 1959 automobile and I should use the old ways on it. Unfortunately I didn't have any gasket sealer. I did have some clear silicone seal though and any port in a storm so I used it not only on both sides of the gasket but to hold the thermostat in place too. Waited 20 minutes for it to set a little, poured the coolant in and no leak. Ran it for 15 minutes and no leak. Finally!
One of my favorite sayings is to never overlook the obvious. I should listen to myself more often. One more thing- the one thing I did do right on this job was to make sure I had several gaskets as backups. Gaskets are cheap. These were cheap but I think in more ways than one, they were thin and seemed more foam than fiber. I'm going to get some better ones and some gasket sealer in case this job doesn't hold and I have to redo it.