Update: Repairs have been completed with no real issues. The O Ring for the thermostat does not retain itself in the grove in the cover and has to be sort of worked with. My assumption is that it will settle around the outside of the thermostat body and that's were the groove is. so....
Only other issue is the shroud that is on the back side of the radiator cannot be installed with the radiator in place due to clearance issues. I forgot to install it during the repair and had to move the radiator from its mount (not easy the way the hoses are attached and routed) but i got it done.
Rest of the parts seemed to go together of, some clearance fitment issues associated with the top and the headlight/grill but it seems ok.
Started the tractor and watched the temperature as it climbed to mid-scale and then back a little as the thermostat (which was new ) opened. Let it run for a while and saw no leaks. Shut it down and look for leaks again, none appeared. Re-started after it sat for about 30 minutes and the same response was noted as above.
So, I think it's fixed. will find out more when I have to actually use it.